Also, look at how the show was having to go into reruns every 7 or 8 weeks, because they were so far behind. That is with not having the TOS optical backload situation, so the show could have easily been in an ever-increasing hole (like taking 2 years to get 25 episodes out) if they had been doing it all in a traditional finish process.
But that also reflects changes in how TV schedules worked. In the 1960s and 70s, you had TV shows run, basically, a new episode every week for 26 (or even more) weeks in a row, then go into the rerun (or preemption) cycle. By the 1980s, the rising importance of sweeps months meant there was motivation to put in reruns on weeks nobody was watching (like, between Christmas and New Year's) and save brand-new episodes for February and, particularly, May. It wasn't just Next Generation going into reruns for a month at a time; it was everything.
I don't recall ANY other show (except MOONLIGHTING, which missed most of its airdates) going on that cycle till the 90s.
If you start in late September, throw up reruns in the holiday weeks and figure maybe one or two pre-emptions, then you still have new programming into the first part of May if you're doing 22 (later if you do 26, which was getting less common in network, but was common for syndication at that point I think.)