If you flush the brake fluid every year or two, you really only need to release 100-200 ml per wheel and power flushing is just not necessary. Any collected moisture, being heavier than brake fluid, will eventually migrate through the fluid and drop to the caliper bores. It is the moisture trapped near brake pistons that can boil on hard braking and cause pedal fade. This is the logic for flushing in the first place.

I always gravity bleed. Neat, dependable, doesn't cause fluid to aerate (when you're bleeding air out of system), one-man job. My method: Fill master with fresh DOT4, put hose on one bleeder and open it about 2 turns, let it run until MC reservoir at half height, close bleeder, refill MC. Repeat 3x, Done until next year.