I also agree that the current Soviet infantry design is bad, it requires radical redesign and ordering to get rid of overlapping and ridiculous roles.
there isnt too much overlap tbh. less so when the new con changes go through.
cons will be very defensive and support. they get great durability buffs with vet and will make better use of cover and merge with the upgrade.
defensive
penals are probably the best 0min unit in the game, but lack durability (they get 15% target size reduction at vet 3, that and to the last man, which scales with loses) but a huuuge 60% accuracy buff between vets 2 and 3
offensive
being able to get PTRS allows the to also be defensive AT, at the cost of some of their AI
guards are very heavy infantry, but need to be stationary to make use of that firepower.
Heavy generalist
shocks are the most durable squad in the game and come with a sole purpose of head on assaulting enemy infantry positions
heavy AI
even if all 4 main squads were available there is a chance that each could find use, sure others can be subbed in, at the cost of efficiency but i call that flexibility rather than overlap.
sure you can slap ppshs on cons have them as a cqb squad, but a single mg burst and they are down for the count.
and penals can fight tanks, but at the cost of AI and they offer no synergy with other units like button does.
the idea is that the jobs can still be done (again, but less effectively) even if you dont have the doctrinal infantry.
the only overlap between penals and cons is the overlap players not wanting to use both are forcing on them. there is room for both!
my only change would be that penals start costing less MP, but with guards mosins and need to buy their SVTs OR PTRS' instead of transitioning between the 2 seamlessly. there should always be a tactical choice in getting AT like there is for literally every other unit that upgrades to it.