Not much hand sanding. Also depends on whether its a 2-turn very round piece or 1-turn warped piece, which may preclude using lathe speed (depends how slow your lathe can go). Very rarely do I hand sand with the lathe not turning.
I use 2” dia mandrels and interface pads, with 2-3/8” discs, on all size turnings. Too cheap to invest in another size, and the 2” gets the job done. Typically use an electric “close quarter” drill with the lowest grit required to get everything cleaned up - lowest grit can vary from 100 to 240.
I then use an electric ros, same 2” pads and dics, starting at ~180 gr, up to highest grit. Its an $80 polisher for auto work.
Air tools work but use a LOT of air - up to the user whether air or electric power is used.
Very important in sanding is keeping speeds down - heat is the enemy. Power sanding tools need a way to vary, and consistently hold, speed. I use a HF router speed control to run power through, so I dont have to try to control the tool trigger to obtain desired speed. Air tools can use a regulator to do the same.