Never let any sandpaper touch the car without a sanding block behind it.... it can be a hard rubber block... or something like a squeegy with some flex...
There is no way anyone in business can really afford the drying time a good paint job requires.... unless you are talking new metal already perfectly straight.... if you have to apply any primer ( either shooting or by hand ) then you need to give that area a couple of weeks to dry BEFORE sanding... because what happens is any area with more depth of primer swells more than the surrounding area... so if you jump in and sand... then when it gives off its acquired carrier it will be LOW....
I have no idea what " a mess" means.... and that might affect advise given on this....
Wax and Silicone Remover = Klix88