Hire a designer based on the thing you want rather than the hours for the thing you want.

Lets say you want a pizza, and contact your favorite pizza place for it. Does it matter how long it took to make ? Or does it matter that you get a good pizza in a timely fashion? Would you be offended if the pizza came faster than it should?

If this holds true for a pizza, why would it not hold true for any other service/good ?