Since I joined BT TV these things have been really painful on the Now TV channels. One of the worst examples being Discovery. Series linking on the YouView just grabs everything, regardless of the season. If you're all caught up and just want to link the new season you can't. You have to waste time checking through recordings and deleting those you've already seen. A 500GB HD fills up fairly quickly when each series link records five times as many episodes as it should. Not to mention the rapid increase in clashes it causes.
Compounding (or perhaps underlying?) this problem is the hit and miss episode metadata. Nothing is marked as 'New' to differentiate it as the new season and there are endless holes and inconsistencies. Some episodes have the wrong description, some have the wrong season or episode number, some have a season but no episode. Some have neither.
I'm not wishing to point the finger at BT here, the metadata was pretty bad on Sky but at least on Sky a new season was marked as 'New' and you could usually series link only the season you wanted. After all, it is called a 'Series link', not a 'To hell with it, just record everything link'.
I don't know if even Sky are to blame for this, it may come down from the content providers. But now Sky have a serious customer for Now TV in BT, perhaps you can put pressure on them to get a grip on the problem?
Sorry for the rant but I've had it with this. Can someone at BT TV please take this up with Sky and their channels?