There's no reason why television time must equate to real-life time. TNG did it, but no need for a series season to amount to one calendar year.
I agree with you in principle, but try telling that to most TV producers these days. Whether we like it or not, it's quite fashionable to tell stories in real time -- even to write in big gaps in the story corresponding to midseason hiatuses and inter-season breaks. For instance, Buffy the Vampire Slayer
's seasons usually started in the fall and ended in the summer, with the summer-vacation months being skipped over. Deep Space Nine
often had a gap of 1-3 months in story time between the events of one season's finale and the next season's premiere, and quite a few other shows have done the same. Just recently, Arrow
had its hero injured just before the midseason break, and the next new episode, aired five weeks later, said that he'd spent six weeks recuperating.
And there are countless shows where events in the previous episode are overtly stated to have happened the week before -- even something like House
, where realistically one would expect the team to devote several weeks to each patient. Even when it doesn't make sense in-story, the real-time conceit is pervasive in television today. It's even pretty common, when a date is mentioned or shown in story, to have it be the actual scheduled broadcast date for the episode (although not always -- this past week's Person of Interest
was set in late November 2012 according to an onscreen date).
True, there are some exceptions, like Lost
, which took maybe 3 seasons to cover a few months of story time, but then jumped forward in time considerably. But they are exceptions to a very popular rule, for better or worse.