My boat polishing was regular, once a year for 33 years.
The bottom of my boats didn't get machine polished, just the top and sides.
I hand waxed the bottom as best I could on the trailer and then finished the job after the boat was on the lift. Since I was often in the water, I didn't use an electric polisher. If the underside of the hull is clean, it's not that difficult to polish and wax by hand. It doesn't get much oxidation below the water line.

Two fiberglass boats were cared for in that way, one for 19 years, another for 14 years and they both looked pretty good when I sold them.
Good move on avoiding the "Ballpark" quote. Those can often come back to haunt you.