I think that networks went to Winter Finales so they could have a dead time for programming and fill it with Reruns and Specials for the Holidays. It lets them stretch their season out so it will go to May ,without having to fill that two months with New programs which saves them production costs for each show. Notice how a full season is now around 13 - 22 episodes ,depending on what company makes it? Back in the 60s a normal run of episodes per season was 39 a year , and by the early 70s it dropped down to 26 a year. The 22 episodes per year were standard since the middle to late 1970s. Now they are talking about running only 10 episodes instead of the 13 we have been getting. At a certain point they can't drop the number of episodes any further because a show can't develop an audience or keep one and the advertisers base model doesn't work any more.