One of the most common questions I get is how much students should practice. While this is a great concern to have, I try to focus more on how the student practices.
A typical way students tend to practice is to play through a song from beginning to end. If they make a mistake, they correct it and keep playing through the song. I find a better approach is to focus in on the difficult section, and practice it until it flows like the rest of the song. Take a look at the video below to get an in depth look at this approach.