I don't have much insight other than that leagues fill a lot more on the weekend and a lot of the strong managers seem to prefer 12 team leagues for a higher chance at free credits. At least that's how it seems to me. Some managers also choose leagues selectively and try for easier competition. The price of the game is too high IMO.
24-team leagues actually have the best return on investment! 7 credits for 24 is better than 3 credits for 12. Yet they are oddly unpopular, I assume mostly because folks are impatient and 12-team leagues are easier to fill/time the start of. Sometimes 24-team leagues will sit in the queue for weeks with only a handful of teams. But once they're more than halfway full, they tend to fill up pretty quick, and you guys are almost over the hump. I'd join myself if I was a bit less busy atm.
I don't like 24 team leagues. I don't like the schedule. I don't like the player pool inequity when you have 24 people because it increases the luck factor in drafts, even in live drafts because there is a big difference between #1-12 and #13-#24.
Certainly a better chance there will be a few patsies to abuse.
Yeah I get the whole investment thing but not a factor for me at all.
But hey that's just me. Many like them--more power to them.
I enjoy 24 team leagues and plan to try to get more going. Currently in one and working on this second one. The card pool is so vast that you don't get burned on as many picks as in the old days and you can recover easier. Lots of quality cards out there. There is also more strategy in the draft due to more competition.
Love me some 24-teamers. The way to go is to make them recurring. Start a new one after the first finishes. If even half the managers re-up the rest will fill in a day or two at most. I started one like this last summer and it's been a lot of fun. And each new league you collect more returners, it snowballs.
I find 24-team leagues can be a refreshing change of pace. The draft, frenzy, and schedule play out a lot differently. A little slow to get them going, but the patience is worth it.