I suppose it depends on the repair shop and how they do business. I purchased my camper from a very good dealership (family run for long-long time) and have great service. I also use another RV dealership much closer to home. Both work the same way:
I take the camper in when something needs to be done. (both) shops will evaluate the needed work, write up an estimate, and then I make an appointment, usually a couple weeks out (and there again, depending on the season of the year to). I take the camper back home with me.
Meanwhile, they order all the parts, get everything ready, and on the appointed day, take the camper in. If for some reason a part is not ready, they (both) are flexible enough to reschedule giving more time for parts to come in. On one occasion, the part came in earlier than expected, and they called me and asked if I could bring the camper in earlier than my appointment (which I gladly did).
Once in the shop, there again it depends on the repair being done, it could be a few hours to a couple days. I had a shower drain repaired (warranty), they had it "in shop" 3 days. I picked it up the 4th day, so I could pick it up on a Saturday and not miss work.
I think generally, for almost every repair I've needed, I've had to wait about 2 weeks before either one could get me in. (there again, this was partly due to ordering parts). Then I'm OK with then having it in shop for a week.
And both shops are VERY good at keep me informed of progress once in the shop.
I think, if you take your camper in and leave it there, 3 weeks is probably reasonable.
Next time, have them evaluate the work, order the parts, make the appointment for the repair, then take it in. This saves a LOT of frustration! Personally, I don't think RV dealerships especially like having customers campers sitting on their lots any longer than is necessary either, especially when they are responsible for safeguarding them and the liability they assume storing it on their premises.
