Current "recharge speed" meaning of milk/wood quantity is useless.
Except maybe for bots who can shear/milk non-stop.
Growing it means player has to shear/milk more often to reap all products. Which is already tedious.
If quantity would grow the 'capacity' of milk/wool it will become much more useful - player will gain more with the same level of tedium.
Example -
with 10 milk quantity cow stores 25l of milk in 48 RL hours
with 40 milk quantity cos stores 50l of milk in 96 RL hours (same 25l per 48 but now you can milk them less often!)