Or should I expect overage or underage?
It really depends on the kind of print job.
If you order 11 sets of a 30 page document that is bound in a cover, you will get 11 copies.
If you order 5,500 copies of a flyer, you might get 5,490, or 5,515. But pretty close to the number you ordered.
If it is a little bit over, you won’t be charged for the extra copies.
There’s most likely a bit of an overrun to allow for spoiled copies. There’ll probably be some spoils—misalignment, smudges, etc.
^^especially if you are ordering a few hundred-or thousand- copies of something