That's a good point actually. In the early multi channel days, channels like that would show a varied schedule. Now they show their few biggest ones back to back every single day.
This is reducing the chances of success of new shows, as people can just watch Big Bang Theory every night instead of watching a new comedy.
It's quite sad that many new shows don't even get a good rating for their first episode. Plus people make their mind up very quickly, so all those hit shows that were actually poor in the first series, wouldn't have become hits in today's world. Wasn't Only Fools and Horses' first series a bit poor.
I disagree with this, sometimes I think it's harder for a sitcom not to get a second series than it is to get one, Count Arthur Strong is a good example, it got next to nothing first time round and got recommissioned, Watson and Oliver was another one. The former at least had critical acclaim, the latter certainly didn't. You've also got Stewart Lee who's had three series and has been recommissioned for a fourth. Yes, the BBC need to get ratings but more than ever they need to be distinctive.
Also as well there are just as many genres in primetime as there used to be, and indeed there's probably more intelligent programming in primetime. You can look at People's Century, the Beeb's history of the 20th Century, in the mid-nineties. That wasn't shown in primetime, the first series was at 10pm -
http://genome.ch.bbc.co.uk/4bc5ddd75e3e4a8d9f0278167580d96f - the second on Sunday teatime -
http://genome.ch.bbc.co.uk/9bd81a37d1094cb780c8377e9e041565 - and the third late on Sundays -
http://genome.ch.bbc.co.uk/e516f287938d4355bc67f2c586ab7054 These days that would be at 9pm on BBC1, guaranteed. I remember when BBC1 showed Finest Hour in 1999 (http://genome.ch.bbc.co.uk/7d116c7f888743da989cf5927e435172) and it was considered quite big news at the time because it was the first history show on primetime BBC1 for years. Nowadays it would be really common.
Some things have got worse, but we do get lots more factual, and intelligent factual, in primetime than we used to.