I think this might vary greatly depending on the hospital policy. DD1 was an emergency at 10:30pm. I stayed 3 nights including (was supposed to be 4 but I fibbed to get out early)
DD2 was elective at 10am. Stayed 3 nights and pushed for them to discharge me early! They recommended four. I would have left at 2 nights if Dd hadn't had low blood sugar.
While I think it is silly to go against a doctors advice if there is a reason, there was no need at all for me to stay for the extra night either time. I couldn't wait to get home. On the other hand, I know plenty of women who have stayed as long as they were allowed to they cannot physically force you to stay, nor should they push you out if you need more time.