Flaws in your squat technique will hold you back from progressing. Overhead squats can improve the squatting pattern and should be a regular part of your strength training program.
The overhead squat requires a more upright posture than the back squat and you're forced to execute the squatting pattern precisely, otherwise the bar would drop to the front or back.
Have a look at the video. You can see the high concentration level of the athlete and accurate execution.
"Every day, I hear someone say, 'I'm too fat. I need to lose 25 pounds, but I can't. I never seem to improve.' I'd hate myself if I had that kind of attitude, if I were that weak. I can lose 10-40 pounds rapidly, easily, painlessly, by simply setting my mind to it. By observing the principles of strict discipline that bodybuilding taught me, I can prepare myself for anything."