Having spent some time working on the hunter circuit I would tell you their warm up ring etiquette is quite different. Gate stewards hold the ring. There is typically no time or set order that if you miss your eliminated. Nobody thinks twice about holding up the ring. They don’t feel pressed for time. Because of this my experience both as a working groom years ago and as rider in some local shows more recently is that a trainer comes in and commanders a warmup jump for all her students to warm up at the same time for a given division. Now, technically you could go over and jump that jump following one of her students if you wanted to, but it is an unwritten rule that you wouldn’t do that if it wasn’t totally necessary and it will make for an awkward interaction. The lack of pressure to get to the in gate creates an environment where riders/trainers sort of take turns with use of a warmup fences “owning” it until they are completely done warming up. (And they are all happy about it!) I assume it doesn’t happen exactly like that at every show, but it does if they can make it work.
Granted it’s been a few years so maybe things have changed, but never I saw jumpers and SS sharing warm up jumps either–rarely saw them sharing even the same warmup ring.
I think it is more likely that there are no small details a lower level rider needs to focus on and prep for to be able to bring on their best performance. Their warm up should be more about trying to get the big picture stuff taken care of, so they can be and usually are quite flexible. Upper level warm ups tend to vary more and be ridden to a plan to meet the quirks of individual horses. They know what they need to get accomplished and there is some determination/competitive factor that presses them to get it done. I never had the problems as a rider in an UL warmup that I’ve had in a LL one.
ETA: No one gives a damn if someone is trotting. What they ARE concerned about is WHY someone is trotting. If you are trotting because you lack confidence as to whether you are able to have basic control in all three gaits it is concerning. If you don’t understand that I’m not sure anyone can explain it to you. I don’t like to be on the road with 15 year old drivers either, much for the same reason.