"an hour of playing in front of a crowd, where the focus is on delivering the best possible performance at the time, is not the same as an hour of focused, goal-driven practice"

A different study tested students on their ability to make clay pots. Some students were scored on the quality of each pot. Others were only scored based on quantity.

The students that emphasized quantity were able to make better pots by the end of the study. By aiming for quantity over quality, they were able to deliver both.

Performing puts a lot of pressure on you and a more direct focus on the mistakes and triumphs that count. I wouldn't be too quick to disregard how valuable it could be, because it forces you to follow through and work on all the important things.