When I did a lot of bike parts painting (40 years ago) I would prepare as many parts as possible in advance, then spend four or six hours spraying them, or spray until I ran out of the amount of paint I had mixed. I was spraying urethanes with hardeners. My goal was to waste as little of the expensive mixed paint as possible.
The paint was a lot cheaper then, but money is money. Today's paint is a LOT more expensive, so cut the waste as much as possible.