I used 22,5 L smartpots for my first grow, and the roots were coming out the bottom and had filled the whole smartpot. Yield was from 143 g to 265 g
https://www.autoflower.org/index.ph...and-auto-frisian-dew.46707/page-7#post-895290
I think bigger grow/root space = bigger plants and higher yield........when it becomes overkill.......good question, and likely strain related, but for some of the "super Autos" like Think Different, Auto Ultima and such, I wouldn't mind giving a 200 L pot a go........