I do as much as I can by machine, started doing it that way back when serious shoulder injuries made hand-application impossible. Now I STILL do it that way. *IMO*, the PC goes over each area a lot faster, more often, and more uniformly than my hand would. And *I* find it a lot easier to move the PC back and forth, easier to use my whole body, which can be important when doing a big job.
For AIO, a foam POLISHING pad works well. This includes Griot's orange pads, CMA/Lake/TOL white, and Meg's yellow.
For some tough areas, like the "gravel guard" (textured paint, often with a satin/flat black finish) on some cars' rocker panels, I use a CUTTING pad. Note that many cutting pads are NOT, in and of themselves, so abrasive that they will mar modern paints, at least not when the pads have a product like AIO on them. I used AIO with a cutting pad on the black painted rocker panels and black plastic lower bumper sections of my Audis- with GREAT results.
For SG, use a foam FINISHING pad. Be especially careful to put it on thin, this can be sorta tricky when applying by machine. If you get it on too thick, give it extra time to dry, use a damp MF for the first wipe, and maybe also use some QD.
IMO, there are worse things you can do than waste a little product. By hand, by machine, do whatever YOU like doing.