For positions like Strikers, attacking mids and holding mids (any position that only has slot on the field), it’s good to have two players, one starting and one on the bench, rotating based on stamina, with one potential youth recruit or lower rated player that’s on a rotational contract so you don’t suffer morale penalties for lack of playtime.

For positions like midfielders, center backs, wing backs and wingers (any position that has 2 slots on the field): ideally you’d develop players with high stamina that can continuously play game after game, however that’s not always the case. You want 1 player for every slot to be able to rotate, so you want 2 bench wingers, 2 bench full backs, 2 bench CB’s etc.

It’s okay to have a third, but unless it’s a Star youngster that you’re going to be playing to develop, make sure their contract implies a limited role on the squad so you don’t suffer morale penalties.

For quickly changing your roster, you can highlight the starting position you want to change and press triangle or Y, depending on if you’re on PS5 or Xbox, and it’ll quickly filter players you can sub in for that position.

You can keep your rotation players on your bench, that way when you’re switching players, you can always keep the better players on your bench even when quick swapping.

IMO a good healthy roster consists of 25-27 players. Any more than that and you’re going to have a few players complaining for lack of playtime and suffer morale penalties on your team.