And this is why blizz created lfr which is broken into wings.
My guild raids 2 hrs 2 nights a week. Most raid 3hr 2 nights a week. Here on my server there are a few guilds that raid just 2hrs a week and one I know of that does 3hr raid on sat. Both are 1 night a week guilds. Then you have those that raid much longer and for more nights. Find what fits you. They’re out there if you look hard enough. That or just do lfr.