it all depends on what you are working on and the situation. there's several ways of achieving the same goal when it comes to finishing. when I buff out a guitar I always wet sand with a buffing pad and water, and then buff it out with the scratch polish and water. the only thing to watch out for with the water, is to try avoid getting the water into screw holes where it can raise the wood up and crack a finish. the water really helps because it evaporates quickly from nitro, plus it keeps the friction down so one can avoid burning the finish or rubbing it off completely during the buffing process.
usually nitro needs time to cure before buffing, but I was able to get away with buffing this drum out because I used water, plus the finish was decently thin enough. If I built up another 4 coats of lacquer I probably would have had to waited a few days before attempting this. Also I should have mentioned that the drum was already finished on the inside of the shell so no where was the water ever exposed to bare wood.
For nitro I would hazard not using gum spirits for me personally just cuz I'm happy with the system I already use and the only thing I know that is safe on nitro for sure is wax, water (in small amounts) naphtha, and mineral spirits. Gum spirits may be totally fine, but I have no reason to test it.

but I do use it in my shop from time to time. I like using it of thinning out a linseed oil finish if I wanted to apply it extra thin for example.
In my experience I find more people have no clue how to apply a varnish. when applying you can glop it on, but the key is wiping away the excess. I usually put it on with a disposable foam paint brush and then remove the excess with a paper towel. the point to this is to make it look even. It takes some time and practice to get good at this, but it's not hard. once it's dry (in about 24 hours) you can then apply the 2nd coat, after 3-4 coats varnish a piece can really look beautiful. here's a Victorian Eastlake dresser with mirror I did a couple years ago completely in a clear gel varnish on top of a walnut and natural stain. I wish I had before pictures cuz this piece look like it sat at a landfill for decades before I refinished it. It was that bad..really. It even has it’s original brass hardware, before I buffed them they were BLACK! this dates around 1870.
