You may want to change things if you're not seeing improvement as soon as you hope. You might be expecting progress too soon. I recommend calculating your progress on a weekly, not daily bases. You may struggle with something one day, then play it with ease the next. If so, you are not alone.
Some days are better than others.
The experienced musician realizes this and makes the best of it. Finally, when your practice schedule is finalized and written down, place it where you can see it. This will help avoid wasting any time trying to remember what to practice, when, and for how long. I believe if you make the effort to be efficient, determined and enthusiastic you will surely see progress. Book 1 by Garey Williams Also published in Modern Drummer, Percussion Notes and Band World.