Metallica’s techs do all the switching backstage. And they do plenty of it. James and Kirk have two AxeFx units each and an old fashioned AB switch because some of their songs require two banks of patches, and you can’t switch between banks without a gap in the sound.i probably misled you and others regarding tracks. they weren't playing studio recordings and not actually playing. Every musician seemingly played their entire parts the entire show, and did so well.
I read an interview by the lead guitarist. He moved from a pedal board and half stacks to a midi controller and half stacks, becuase the pedal board was too complex to stomp quickly. now he has moved to where his effects are electronically controlled with the click track, so they change at the point in the song when they should. he is still playing, he just doesn't have to change things on a board. if you see the metallica video I posted, it's the same idea. players can play without having to worry about stomping pedals, that can get very complex.
So yeah, switching is very easy when you don’t have to do it yourself.