All of this. He rarely takes a medical time-out when he’s winning, but very regular when he’s struggling. I believe Murray even passed comment on it a few years ago. It’s at best shady gamesmanship, at worst a form of cheating. He spat the dummy when he was refused by an umpire at one match.
And as you’ve said, could barely complete a 5 set match, then suddenly became some kind of iron man overnight.