if anything I've had both my RM and LM falling back to make 5212, but I have them both to stay back. if you have unbalanced tactics on your wingers they tend to "rotate" the formation to a 4 at the back setup. I used to play 352 with my RM set to come back when needed and it worked wonders last year fluctuating between 7 attackers and 6 defenders
this formation has been a revelation for me. 442 was working well, but for the last 2 or 3 weeks the gameplay has fluctuated from alright to atrocious, mostly the latter after 10 wins. I switched to this as my main formation, and not only has the game felt so much better and I've won more games, but you're right in that it is extremely fun to play! I've thrown Walker into RCB alongside Gomez and Varane, with Mendy and Allan in CDM. Fati and Moura on the wings, with Wijnaldum in CAM, and Zola/Werner upfront. I feel like this formation is miles better than anything else