&gt; So, it wasn&#x27;t surprising to me to learn that the Grand Masters are Grand Masters because of their memorization of opening sequences, the depth of that memorization, and when to use which variation.<p>This is not true. Opening knowledge is a common deciding factor in games between GMs, but that&#x27;s only because they&#x27;re already so good at everything else. A low GM actually probably has a smaller skill margin over other players in terms of openings than in other areas of the game: as someone that&#x27;s arguably a decent amateur (~2200 USCF) and has played against several GMs, I would prefer my chances in a game where we both have our opening knowledge versus one where neither of us has opening knowledge.