diff --git a/aircox/management/commands/sounds_monitor.py b/aircox/management/commands/sounds_monitor.py
index 28911f4..8bbe58c 100755
--- a/aircox/management/commands/sounds_monitor.py
+++ b/aircox/management/commands/sounds_monitor.py
@@ -258,42 +258,6 @@ class Command(BaseCommand):
             logger.info('%s, %s: %s', str(program), str(component),
                         ' '.join([str(c) for c in content]))
 
-    def add_arguments(self, parser):
-        parser.formatter_class=RawTextHelpFormatter
-        parser.add_argument(
-            '-q', '--quality_check', action='store_true',
-            help='Enable quality check using sound_quality_check on all ' \
-                 'sounds marqued as not good'
-        )
-        parser.add_argument(
-            '-s', '--scan', action='store_true',
-            help='Scan programs directories for changes, plus check for a '
-                 ' matching diffusion on sounds that have not been yet assigned'
-        )
-        parser.add_argument(
-            '-m', '--monitor', action='store_true',
-            help='Run in monitor mode, watch for modification in the filesystem '
-                 'and react in consequence'
-        )
-
-    def handle(self, *args, **options):
-        if options.get('scan'):
-            self.scan()
-        if options.get('quality_check'):
-            self.check_quality(check = (not options.get('scan')) )
-        if options.get('monitor'):
-            self.monitor()
-
-    @staticmethod
-    def check_sounds(qs):
-        """
-        Only check for the sound existence or update
-        """
-        # check files
-        for sound in qs:
-            if sound.check_on_file():
-                sound.save(check = False)
-
     def scan(self):
         """
         For all programs, scan dirs
@@ -314,10 +278,6 @@ class Command(BaseCommand):
             )
             dirs.append(os.path.join(program.path))
 
-        # extra scan for files that are not in programs' dir anymore
-        # TODO
-
-
     def scan_for_program(self, program, subdir, **sound_kwargs):
         """
         Scan a given directory that is associated to the given program, and
@@ -350,6 +310,16 @@ class Command(BaseCommand):
                                exclude(pk__in = sounds)
         self.check_sounds(sounds)
 
+    @staticmethod
+    def check_sounds(qs):
+        """
+        Only check for the sound existence or update
+        """
+        # check files
+        for sound in qs:
+            if sound.check_on_file():
+                sound.save(check = False)
+
     def check_quality(self, check = False):
         """
         Check all files where quality has been set to bad
@@ -419,4 +389,29 @@ class Command(BaseCommand):
         while True:
             time.sleep(1)
 
+    def add_arguments(self, parser):
+        parser.formatter_class=RawTextHelpFormatter
+        parser.add_argument(
+            '-q', '--quality_check', action='store_true',
+            help='Enable quality check using sound_quality_check on all ' \
+                 'sounds marqued as not good'
+        )
+        parser.add_argument(
+            '-s', '--scan', action='store_true',
+            help='Scan programs directories for changes, plus check for a '
+                 ' matching diffusion on sounds that have not been yet assigned'
+        )
+        parser.add_argument(
+            '-m', '--monitor', action='store_true',
+            help='Run in monitor mode, watch for modification in the filesystem '
+                 'and react in consequence'
+        )
+
+    def handle(self, *args, **options):
+        if options.get('scan'):
+            self.scan()
+        if options.get('quality_check'):
+            self.check_quality(check = (not options.get('scan')) )
+        if options.get('monitor'):
+            self.monitor()
 
diff --git a/aircox/management/commands/streamer.py b/aircox/management/commands/streamer.py
index a1c6f45..a36b576 100755
--- a/aircox/management/commands/streamer.py
+++ b/aircox/management/commands/streamer.py
@@ -94,8 +94,6 @@ class Monitor:
         self.station = station
         self.__dict__.update(kwargs)
 
-        now = tz.now()
-
     def monitor(self):
         """
         Run all monitoring functions.
@@ -191,16 +189,18 @@ class Monitor:
                 comment = current_sound,
             )
 
-        # tracks -- only for streams
-        if not log.diffusion:
-            self.trace_sound_tracks(log)
+        # trace tracks
+        self.trace_sound_tracks(log)
 
 
     def trace_sound_tracks(self, log):
         """
-        Log tracks for the given sound log (for streamed programs).
+        Log tracks for the given sound log (for streamed programs only).
         Called by self.trace
         """
+        if log.diffusion:
+            return
+
         tracks = Track.objects.get_for(object = log.sound) \
                               .filter(in_seconds = True)
         if not tracks.exists():
diff --git a/aircox/models.py b/aircox/models.py
index c1a0cc7..2b1819c 100755
--- a/aircox/models.py
+++ b/aircox/models.py
@@ -15,6 +15,7 @@ from django.template.defaultfilters import slugify
 from django.utils.translation import ugettext as _, ugettext_lazy
 from django.utils import timezone as tz
 from django.utils.html import strip_tags
+from django.utils.functional import cached_property
 
 from taggit.managers import TaggableManager
 
@@ -68,6 +69,9 @@ class Related(models.Model):
         'related_type', 'related_id',
     )
 
+    class Meta:
+        abstract = True
+
     objects = RelatedManager()
 
     @classmethod
@@ -77,9 +81,6 @@ class Related(models.Model):
         """
         return GenericRelation(cl, 'related_id', 'related_type')
 
-    class Meta:
-        abstract = True
-
 
 class Nameable(models.Model):
     name = models.CharField (
@@ -87,6 +88,9 @@ class Nameable(models.Model):
         max_length = 128,
     )
 
+    class Meta:
+        abstract = True
+
     @property
     def slug(self):
         """
@@ -99,9 +103,6 @@ class Nameable(models.Model):
         #    return '#{} {}'.format(self.pk, self.name)
         return '{}'.format(self.name)
 
-    class Meta:
-        abstract = True
-
 
 #
 # Small common models
@@ -460,6 +461,8 @@ class Stream(models.Model):
     )
 
 
+
+# BIG FIXME: self.date is still used as datetime
 class Schedule(models.Model):
     """
     A Schedule defines time slots of programs' diffusions. It can be an initial
@@ -499,8 +502,9 @@ class Schedule(models.Model):
     )
     timezone = models.CharField(
         _('timezone'),
+        default = pytz.UTC,
         choices = [(x, x) for x in pytz.all_timezones],
-        max_length = 100, blank=True,
+        max_length = 100,
         help_text = _('timezone used for the date')
     )
     duration = models.TimeField(
@@ -529,35 +533,17 @@ class Schedule(models.Model):
         verbose_name = _('initial schedule'),
         blank = True, null = True,
         on_delete=models.SET_NULL,
-        help_text = 'this schedule is a rerun of this one',
+        help_text = _('this schedule is a rerun of this one'),
     )
 
-    @property
-    def local_date(self):
-        """
-        Return a version of self.date that is localized to self.timezone;
-        This is needed since datetime are stored as UTC date and we want
-        to get it as local time.
-        """
-        if not hasattr(self, '_local_date') or \
-                self.changed(fields = ('timezone','date')):
-            self._local_date = tz.localtime(self.date, self.tz)
-        return self._local_date
 
-    @property
+    @cached_property
     def tz(self):
         """
         Pytz timezone of the schedule.
         """
-        if not hasattr(self, '_tz') or self._tz.zone != self.timezone:
-            import pytz
-            if not self.timezone:
-                self.timezone = \
-                    self.date.tzinfo.zone \
-                        if self.date and hasattr(self.date, 'tzinfo') else \
-                    tz.get_current_timezone_name()
-            self._tz = pytz.timezone(self.timezone or self.date.tzinfo.zone)
-        return self._tz
+        import pytz
+        return pytz.timezone(self.timezone)
 
     # initial cached data
     __initial = None
@@ -881,16 +867,14 @@ class Diffusion(models.Model):
         """
         return self.start
 
-    @property
+    @cached_property
     def local_date(self):
         """
         Return a version of self.date that is localized to self.timezone;
         This is needed since datetime are stored as UTC date and we want
         to get it as local time.
         """
-        if not hasattr(self, '_local_date'):
-            self._local_date = tz.localtime(self.date, tz.get_current_timezone())
-        return self._local_date
+        return tz.localtime(self.date, tz.get_current_timezone())
 
     @property
     def local_end(self):
@@ -899,9 +883,7 @@ class Diffusion(models.Model):
         This is needed since datetime are stored as UTC date and we want
         to get it as local time.
         """
-        if not hasattr(self, '_local_end'):
-            self._local_end = tz.localtime(self.end, tz.get_current_timezone())
-        return self._local_end
+        return tz.localtime(self.end, tz.get_current_timezone())
 
     def is_live(self):
         return self.type == self.Type.normal and \
@@ -1289,7 +1271,6 @@ class LogQuerySet(models.QuerySet):
         #                 models.Q(date__lte = end))
         return self.filter(date__gte = start, date__lte = end)
 
-    # TODO: rename on_air + rename Station.on_air into sth like regular_on_air
     def on_air(self, date = None):
         """
         Return a queryset of the played elements' log for the given
@@ -1528,9 +1509,7 @@ class Log(models.Model):
         This is needed since datetime are stored as UTC date and we want
         to get it as local time.
         """
-        if not hasattr(self, '_local_date'):
-            self._local_date = tz.localtime(self.date, tz.get_current_timezone())
-        return self._local_date
+        return tz.localtime(self.date, tz.get_current_timezone())
 
     def is_expired(self, date = None):
         """