90 ammo is not too much. It is good! You just have to find a different strategy and see what works and what does not! Redistribute your muni spending.
(also, shocking newsflash: All 4 factions are heavily ammo dependent to make their inf potent)
Volks by default without weapon upgrade, just like Conscripts are good early game.
BUT When they scale and when do not have upgrades. They become arguably the worst unit on the field as they get outperformed by other infantry. Volks only does well when they obtain STG upgrade. Without it, they are easily outmatched mid-late game, just like Conscripts. Grens you potentially can halt for the upgrade while Volks you need the upgrade fast!
Applied exactly to that of Conscripts and Volks, they scale badly against inf without upgrades mid-late. By default they are not reliable. Without upgrades, they cant maintain or hold ground. They play only a supportive role. Volks with upgrade, takes them out of that supportive role in adaption for aggressive role.
The thing about Axis is that you need ammo/weapon upgrade early to combat most Allied infantry units. Allies can make do without them but potentially do way better with them than Axis. That is why they have side tech. UKF weapon lmg is not that great an upgrade. Tommies without weapon upgrade are exceptionally great. 5 man does more than a weapon upgrade. It is somewhat compensated!
USF Riflemen become arguably the best infantry late game because they outmatch most inf with 2 bars. Vet plays even a stronger role. As they shred on the move, and their accuracy on the move is the highest. Best faction also to chase down retreating squads. They become almost the elite unit when Volks only reliance late game is its Vet. Their weapon upgrade late game wont play much of a role of aggression anymore!
OKW, you cant rely on their support weapons as much as other and Sturmpio (their other mainline infantry is unreliable as they die pretty easily in comparison to Volks) infantry. You have to rely on Volks as they are versatile and the only thing that you have to make do with.