Good question, in theory I guess contractors and retail customers should be treated the same by a repair shop, retail clients pay full price for equipment usually plus full price on repairs so in theory they are worth more to the shop, contractors tend to spend a lot more but generally get some discounts on purchases and repairs.
A lot of contractors I know expect priority service from a repair shop and I suppose I fall into the same boat, my livelihood depends on my equipment working, however unlike some other contractors I have 2 of everything so repair turn around times are in theory less urgent for me. I would expect to not wait any longer than a week for a repair job to be carried out though.
A lot also depends on the relationship you have with your repair shop, I have good relations with two shops, there is a permanent discount on all my repairs and purchases of parts, furthermore any repairs tend to be done within 1 day so I can't complain.
Competition in my area among repair shops seems pretty fierce and they all want the contractor's work so this is also a factor I guess.