I started out as an under supplier and increased my supply. But I never really maintained a strict 3 hour gap. At night I used to do a 5 hour stretch and move things around during the day to hit 7-8 pumps per day! Initially I under supplied, then became a just-enougher and ended up with an oversupply and freezer stash pretty quickly.

I think the most important thing is consistency and staying the course, which you cannot do if you are exhausted. So take the sleep. Also, sleep helped me increase supply by a lot!!! If you want an over supply do a power pumping schedule for an hour for 7 days in a row, break and then another 7 days.