I think that we've talked about this before, but one thing I'd say is that when you got this "new" long-form telly thing that took off with, I dunno, Sopranos and Six Feet Under and various other things, it was a new format that left behind the old cliches and wrote its own rules... but then of course these rules ended up being codified and becoming new cliches of their own.
One thing I've noticed is that a lot of series start off with the first episode being really good, maybe the second too, then they tread water until approaching end, at which point they pick up a bit for the last couple of episodes and put in a cliff-hanger - or if not quite as crude as that, something that needs to be resolved - so as to get a second series.