The "don't blunder" advice applies to sports as well, where you hear it phrased in non-tautological ways frequently, typically something like "you need strong foundations."
Even at the peak of college level, I remember winning and losing games because someone did something that you mostly stopped doing soon after learning the sport, like pass to a teammate who wasn't looking, or fumble the ball in a preventable way, or things like that. Some teams focused on fancy plays and corner cases while their fundamentals still failed frequently, leading to more losses due to bad fundamentals than than wins due to good advanced plays.
That's how I read the "blunders" stuff. There's some small set of a priori known foundations you need which are fairly simple to keep from going wrong, which nonetheless lead to a large portion of failures/points given up/whatever.
Even at the peak of college level, I remember winning and losing games because someone did something that you mostly stopped doing soon after learning the sport, like pass to a teammate who wasn't looking, or fumble the ball in a preventable way, or things like that. Some teams focused on fancy plays and corner cases while their fundamentals still failed frequently, leading to more losses due to bad fundamentals than than wins due to good advanced plays.
That's how I read the "blunders" stuff. There's some small set of a priori known foundations you need which are fairly simple to keep from going wrong, which nonetheless lead to a large portion of failures/points given up/whatever.