Relating to this, a big realization for me was in highschool when I was given the advice by an elder sibling that I didn't need to try to do everything perfectly if I had other important things to do. Eg. it's okay to take a small hit on one class's grade by skipping a weekly homework assignment if it means being able to focus on the term end project from another class.

In hindsight it seems kind of obvious, but I was so used to the parental pressure to just do everything perfectly from my earlier years that it had never occurred to me to prioritize. Although I suppose it does still require you to have a mature sense of priorities, since skipping all assignments to party every day is obviously not healthy.