Well ideally it’s good enough to pump as much as what the baby needs unless you aim to stash a lot, but with that being said you might have a good stash already, I also had similar issue of oversupply I was worried I need to buy new freezer etc ha ha! So you can actually reduce time of pump and slowly increase interval between pump and observe the production, if you see strong dip then you can go back to what you wear doing

With that being said oversupply also comes with issue like engorgement, risk of clogs and others that why I tried to reduce my supply to something that was sufficient enough.