For a musician or any other performer, daily practice is an important part of being prepared for the gig. It also can (and should!) be enjoyable in and of itself. Because performing on an instrument is a physical activity, the physical need for daily practice should not be ignored. Practicing also helps the musician develop their mental focus.
In college, I was highly encouraged to practice for at least 4 hours a day, if not more. This was due to the fact that the course load of a music major made it impossible you to be successful without that much daily effort. Now that I’m out of college, I don’t have that kind of daily time available for practice. I need to be much more focused and deliberate about what I practice.
The following article by Dr. Noa Kageyama explains how to be effective with minimal time. One tip he gives, which I also use, is to set and work towards goals. Being aimless about what you’re working on may produce results over time, but a clear goal will allow you to focus and work specifically toward mastery. You can find his article here: http://www.bulletproofmusician.com/how-many-hours-a-day-should-you-practice/
What are some tips you have for effective practice or mastery of a subject?