Practicing is a musician's time to make what they have been taught their own--to build a relationship with a technique, method or piece of music.
One of the essential ingredients in practicing is repetition. Where too much repetition becomes a problem is at the point of repeating something without assessing it, and finding and putting into play the necessary components to improve it. Without this kind of reflective approach, the repetition becomes redundant and soon can turn into a rut, which is not a useful kind of repetition, often referred to as "spinning your wheels."
To get out of a rut, find a new route.