Generally, the smaller the better. Smaller gap between the executives and the animators and smaller teams means they have to keep the workers happy because if a few leave, the whole production grounds to a halt.

Ehh… nowadays most studios outsource a LOT, so losing talent isn’t really that threatening. Afaik KyoAni and Ghibli are the only studios who barely outsource anything, other ones may have some “regular” director or animator but most of them are just freelancers.

Their bank account is much more important than talent retention, sadly (and most studios do pretty badly under that aspect as well, as most of the money goes to committees).

Anime industry is just a mess in general, it’s a miracle they even manage to release great products from time to time.