The answer varies greatly. If you have just the one snake, and you wait the appropriate time after feeding (48 hours or so, depending on meal size), there's zero issue with handling once a day.

Like anything you just have to read the signs, If your ball python seems stressed by your handling, make it less frequent, but do keep at it. Handling definitely improves their disposition. When not digesting. I tend to handle my girl once a day for short periods. She seems very chill with it, and it keeps her moods mellow.

I've known snakes who were previously handled frequently to go to a new owner, who doesn't handle them, and they regress into a state of being nippy ect.