Overlearning is a pedagogical

Pedagogy

Pedagogy is the study of being a teacher or the process of teaching. The term generally refers to strategies of instruction, or a style of instruction....

 concept according to which newly acquired skills should be practiced well beyond the point of initial mastery, leading to automaticity

Automaticity

Automaticity is the ability to do things without occupying the mind with the low-level details required, allowing it to become an automatic response pattern or habit. It is usually the result of learning, repetition, and practice....

. Once one has overlearned a task, one's skill level is higher than the challenge level for that task (see Control region in the graph).
The Yerkes–Dodson law predicts that overlearning can improve performance in states of high arousal.