In the past, I occasionally push MR or ML up and don't find any major problem.

Now all my teams always keeps 4 wingers including 2 AMR and 2 AML. These players are key players of my teams for a long time.. All these players have dual role. I prefer 1 or 2 of them can also play AMC and other can play MR or ML.

With these players in team, I usually play 4-5-1v or 4-3n-2(AMR/AML)-1, but can switch to other formation like 4-4-2 easily. This greatly improve flexibility. I do not want too many AMC because I personally do not like formation focusing in central. Besides, for example, with a AMC/AMR and AMR/MR can play together with least conflict in positions.