Right. Understanding and performance are both necessary for mastery.
Without understanding, if you ever misremember something, you will be unable to find and correct your mistake. And if you forget something, then it's gone, until you find a textbook and memorize it again.
On the other hand, solving larger problems in math requires solving dozens of smaller problems along the way. When you have to stop and think about the small problem, you lose the big picture, and then you need to backtrack, which slows you down and frustrates you.
Understanding needs to come first, but practice is the necessary second step.
Without understanding, if you ever misremember something, you will be unable to find and correct your mistake. And if you forget something, then it's gone, until you find a textbook and memorize it again.
On the other hand, solving larger problems in math requires solving dozens of smaller problems along the way. When you have to stop and think about the small problem, you lose the big picture, and then you need to backtrack, which slows you down and frustrates you.
Understanding needs to come first, but practice is the necessary second step.