The idea is good, but the implementation method is really not the best.
I think this variant will be better(imo).
Each squad has its own personal timer.
A squad of 9 people with FG42-2 will wait a conditional 40 seconds.
A squad of 3 snipers with starting bolts - 4 seconds.
You can either take a squad of snipers in 4 seconds, or wait another 36 and take a squad of 9 people.
If it weren’t for the stupid idea of monetization with slots, then it would be possible to take 3 units with light weapons, 3 with heavy (in the sense of level).
And depend of situation you can choose best variant.