At the LBS where I work, our no-show rate for appointments is usually about 1 out of 3. It's a really bad way to stay profitable, since we then have to reorganize the schedule, move the appointment and push other stuff out of its way, contact the customer... I understand you'd like to keep your bike in the meanwhile, but I also understand why an LBS will insist you leave it if you want a place in the queue.

As for collecting dust or dents... if you're getting a tune-up, your bike gets cleaned. And where I work, your bike has its own 32-inch-wide personal space to hang in, so it's not likely to get banged up.

Anyhow, average lead time in the busy season might be 2-3 days (a big improvement over what we were doing a couple years ago), but it'll depend on whether we need to order in some parts for the job. We order from our distributors weekly, which can delay the parts anywhere from a day to a week, depending on which distributor and which warehouse has what you need. Next season I'm going to push for us to order twice weekly from our closest distributor when volume's high.

Bikes vary... trust me