Those squads building is almost the same with my FM squad building model, I use 2 GK + 7 DEF +5 MID + 5 ATT, only 1 midfielder missing (Miretti/Adzic injured)
I play 4-3(CM)-3(ST) Narrow, so for MID and ATT 5 players is enough while 6 is too much. But my key to make it feel like 6 players in each department is to train one of my good finishing midfielder as a striker and training 1 of my best passer striker as midfielder so it camouflage as 6 players for 3 position each. But actually only 5 players for mid and att
7 players DEF with at least 3 or 4 can play on the right, 3 or 4 can play on the left and 4 or 5 can play on the center (DRLC will ultimately helpfull, player like Djalo)
My first team only consist of 2 GK my first team GK and backup GK, backup GK will play in the cup or against lower side (I allocate him 1500 minutes per season)
I have another GK with Model Citizen with pretty good attributes (I dont care if he has low star rating, the important thing is his GK attributes), this one come into my reserve and become tutor for all my reserve player and he act as 3rd GK
I actually love build squad with low numbers as most players will get great game time, especially with 5 substitution more subs