Here in Colorado, local diving is not a really popular activity, and most of us that do it have the ability to do our own fills. I am associated with a shop, but I don't know how they do fills for people who bring their own tanks. I do know that all the standard fills we use for instruction are always short. That is because the compressor is automatically set to 3,000, and after it cuts off, they generally pull the tanks, which means the pressure will drop as they cool. Because the tanks are primarily used for instructional purposes, it isn't a huge deal. (Although I have decided that I am going to jack up my students' tanks for OW from now on.) I hope the shop does something similar for the customers who bring in their tanks, but I don't know.
As for your coming in and waiting, that should not be an issue at all. I often find myself in the position of filling a set of tanks with nitrox for our "technical expeditions." I know how much oxygen to put in for a 3,000 PSI fill. Then I put them on the compressor and fill to 3,200, knowing that if I do, it will drop to 3,000 as it cools.
If your shop wants to give you a 3,000 PSI fill and knows you are waiting, it should also know roughly how much to overfill to keep a customer happy.
As for your coming in and waiting, that should not be an issue at all. I often find myself in the position of filling a set of tanks with nitrox for our "technical expeditions." I know how much oxygen to put in for a 3,000 PSI fill. Then I put them on the compressor and fill to 3,200, knowing that if I do, it will drop to 3,000 as it cools.
If your shop wants to give you a 3,000 PSI fill and knows you are waiting, it should also know roughly how much to overfill to keep a customer happy.
