3 x 3 question

Hey guys so im in the process of changing out the tranny oil since first to second has become violent. It may be a little late for that now but i figured hey whats 50 bucks compared to buying a used tranny. Anyway my question is when draining the fluid does it typically stop at 3 quarts or does it drain more and i am supposed to stop at 3 quarts?

The reason i ask is i drained 4 quarts luckily i bought 4 quarts. What im not sure is whether it has been over filled all this time from the tranny shop?

Any advise before i put that 4th quart would be appreciated. Thanks