the quality, not the longevity, of one's practice is what is important*
Often, if we "make" the time to practice, we think it sufficient simply to sit to the harp. And sometimes, we are lucky just to do that much. But it is important that we infuse our practice time with Quality not just a quantity of minutes.
This means we have to have a plan, a "schedule" if you will, for what we'll be doing while we're there. And we have to know and understand what that plan will bring to our improvement. We don't just rip through music to check the box and say we're done.
* I believe the original quote from Dr. King was, "The quality, not the longevity, of one's life is what is important." That too bears reflection.