I had an excellent art coach for a while. Alexander Steenhorst. One trick he showed was to, immediately after drawing something, write what you note about the drawing. Write down what you feel worked and why, and also write down what you think is off and why.
Do this in an aloof fashion. Don’t feel bad you made mistakes! They point you at something you can focus your attention on to improve.
Devise a plan to improve that. Devote a page to practicing one thing you found you needed to practice.
It also works because it removes that sad feeling you tend to have when you see something wrong with your drawing. Something positive came out of it: a plan to improve it!
That’s the habit we have to unlearn: feeling bad when we notice we did something wrong. Take a step back, look at it objectively, and devise a plan to improve it.