Comedy is very different to drama/general entertainment, though. Besides, I think if some of our series had 12/18 long seasons, they'd be rubbish. Fawlty Towers was only 12 episodes long, but one of the greatest British comedies with a high re-watchable value. It is very British though, but I think it's good that quite a lot of our comedies have finished with ratings as high as they were in earlier seasons and with good quality still showing.