You're on the right track Nelson, especially if you're building single ukuleles. I find using the RO sander to be about 4X faster than doing it by hand and the finish looks better as well. The problem with hand sanding is picking up stray pieces of larger grit or other contamination, producing long, deep scratches that won't show unit you progress to the higher grits. With a ROS the scratches made by sanding are tiny little circles, easier to buff out. An ROS is faster but that also makes it more dangerous. In either case it's important to keep your environment as clean as possible when sanding and buffing finishes. I have dedicated sanders that never see wood, only lacquer, and are sealed in plastic bags when not being used.
BTW, I believe that 2400 micro mesh is equivalent to about P800. NEVER sand any finsh dry. To flatten, I'd rather start with something finer, say P1000 or even P1500 (Micro Mesh= 3200). I don't care for the cushioned (cloth) backing of MM for flattening, preferring a more rigid paper like Mirka. Mirka papers are excellent, very consistent, long lasting and will not pill if you add a few drops of Dawn detergent to your water.
You talk about six coats of lacquer total but that really tells us nothing about the thickness. That will vary depending upon the brand of lacquer, the ratio of reduction, and your technique in spraying. If you've got orange peel you'll be sanding more of your finish. I like my final coats to build up to about .006" which will sand down to about .004" when I'm finished. Many sand-throughs can be eliminated by spraying your corners first, then spraying the overall instrument. Sharp edges do not like to hold lacquer and this method makes sure you'll have adequate coverage on those critical parts. Also, never sand your edges, they'll take care of themselves. I power sand all my finishes using either Abralon or Trizact (after first hard blocking with 1000) up to P5000 before buffing (two compounds) and rarely have a problem with sanding through. They say that is your butt isn't clenched all during the final sanding process, your finishes are probably too thick.
You're working right on the edge all the time.
Power sanding lacquer is wonderful in a production environment and I wouldn't do it any other way. If you are building the occasional instrument and have more time than experience you might be better off doing it by hand. Good finishes are an art that is only learned through lots of practice. It's by far the hardest thing I do. Good luck.