A good rule of thumb is unless its a show car or you want it looking its best to sell just use a good paint sealer and wax and leave the buffer (any buffer, DA and rotary) and compound alone. A light buff job with polishing compound once in a great while is okay.
Paint gauges are all well and good but on repainted panels or a whole paint job the value of the gauge diminishes greatly, it cant be trusted.
When I paint I use extra clear for wet sanding and buffing when its done, on expensive paint jobs I unmask it, sand the clar super flat then remask and spay 2 more coats. OE clear is very very thin and some of it is soft, not something you want to go Micheal Myers on.
The best thing you can do is prevent scratches by using a bucket guard, using sponges or mitt for upper panels and lower panels and a dedicated wheel cleaning set and stay clear of brush car washes.
Never wipe anything off the paint dry or God forbid a paper towel or some old rag they are worse than 3000 sandpaper.