Employee mistints

Curious on what you guys do or what there is to do if you have an employee that has an extremely high mistint. Everyday this employee works there’s at least 2-3 mistints on their part. Usually it’s oh I tinted the wrong product or oh I tinted the wrong color or sheen. I usually don’t care about mistints but I feel it’s getting out of hand. In the month of November that employee has 26 mistints.