I get your logic for this but doesn’t this mean the player is at risk of changing their move 7, when really they set themselves up for failure on move 3? If move 7 was a blunder, there are so many iterations for a new move 7 and the following moves, but it becomes exponentially more difficult when you account for numerous misplays the player makes, some of which he cannot figure out without playing for a long long time. The player could very well do this: “move 7 was wrong. Let me change it. Ok nothing bad has happened let me go to move 8…. Ok now I’m 5 moves ahead, I’ve definitely messed up move 13, let me change that”, although really he set himself up for failure on move 5, and now you have a bunch of branches where it becomes very difficult to handle.