To give you the other side, when I was working at a shop, I spent as much time as the customer needed with a sale. Whether it was a $900 or $9000 sale. Didn't matter so long as the customer was satisfied with what he/she was purchasing. At a minimum though, probably about an hour from arrival to purchase.
Custom frames/builds always take longer because of the inherent time devoted to build list and particularly to fitting a custom frame.