How long does your LDS take to service your regs? Regularly, yearly service, under warranty?
The actual time required for routine annual regulator service is minimal - certainly less than an hour for a first stage and two second stages, IF the parts kits are in stock, and IF there are no problems, and IF the reg doesn't have to be ultrsonically cleaned, etc. But, depending on the shop, the service may be done by sending the reg out to another local service center, which takes extra time, or by having a contract technician come in to do the service, which may only occur once a week (or less frequently), or by waiting until there are several regs to be serviced, and doing them all at once. So, the answer is - and I am sure you have never heard this before - 'it depends'.
I service my own, so it takes minimal time, except I like to use the workroom at my LDS which requires me to drive over there at a time when it is not in use. We have a contract technician that we use, and he comes in once a week (on the day the shop is closed). Unless there is a backlog of work, he usually gets everything done on his service day, so the turn-around time for customers is anywhere from 1 to 7 days. If he gets backed up or can't come in one week, it may mean a two week turn-around time for the customer.
However, if a customer comes in on Wednesday, and says they have a coastal dive trip on Saturday, and they have a problem (e.g. IP creep and slight free flow) and really need that reg back quickly (and are nice about asking if we can help, not DEMANDING that we jump to their needs), one of the other shop staff will probably be able to address the problem in as little as a day.
Does it take longer if you didn't buy your regs at that shop?
No, with a caveat. We don't put regs bought elsewhere at the end of the service line. But, we may not have the parts kits in stock for a regulator brand that we don't sell. In that case we either send it out to another local service center (usual practice), which takes extra time, or order the parts, which takes extra time.