The 80% League
From Hockey Tactics 2023 - The Playbook by Jack Han, but clearly applicable to far more domains than sports:
The 80% league
Future NHL coach Martin St. Louis once told former NHL coach Guy Boucher "the NHL is an 80% league."
What the then-Tampa Bay Lightning forward was telling his coach is that no NHLer could sustain 100% effort throughout the regular season. Experienced players instead manage their energy, pick their spots and peak at the highest-leverage moments.
The same applies to any other line of work. 80% effort is a solid, sustainable level for any professional. A 100% sprint, necessary at critical times, then requires a cooldown period (40-60% effort) or even total rest (0%). Violating the principle in the long term leads to people breaking down or burning out. It's the same in every line of work.