You’re correct. The more aggressive version of this is called “move pruning”, effectively cutting off entire branches of the search tree. Techniques like this a

You’re correct. The more aggressive version of this is called “move pruning”, effectively cutting off entire branches of the search tree. Techniques like this are essential for the strength of modern chess engines, but like every heuristic, they can be wrong. Sometimes, the engine makes a mistake because it literally didn’t consider a certain response.