Comment by iamthirsty

Again, I think there is a misunderstanding of what the saying is used for.

In chess, it's specifically used for saying "even with the best defense possible, you will be mated no mater what in a maximum of X moves." Computers use this definition as well. If Stockfish says # in 6, that means there is an indefensible path to mate available, and with the best play of the opponent will take 6 moves.

It's not a "Mate in X, probably."