Hard to say, depends on the rating of your players. It is not easy to keep all the players happy if they have high rating. I usually have 22 players so each position has one backup and always rotate them. You need to calculate how many games each players need to avoid concern and try to use 3 subs every match.
Team with many high - rated players will develop concern at certain point because they need a lot of games. I had many players with concern in one team (ranging from level 1 to level 3) and I decided to focus on dealing with their concern rather than competing for the title in more or less competitive GW.
Having experienced many players with concern, I think the best way to deal with it is: just let it be 😆. You can deal with them once they develop concern. Just try to rotate them so only one or two players develop concern, then you focus on those two to lower their concern, maybe in exchange other players develop concern. No problem, just do the same for new concern. In other words, you rotate the concern so the concern is at most level 2 but limited only to few players (1 or 2).
Hope my post doesn't confuse you 😁