Practicing is the most important factor in making progress as a musician. The lesson only happens once a week, but practice should occur every day. Below are a couple of pieces from an article about practicing by Peggy Swingle, a Suzuki piano teacher/trainer from the American Suzuki Journal, Summer 2004:

"While what is presented at the lesson is key, unless it is reinforced and integrated all week it is of little use. Yet successful practicing remains a mystery to many parents. Practice time all too often is filled with tension, struggle and a battle of wills..." 

"...the reason to practice is to make something easier. It seems so simple, yet this reason has in it the potential to make practice interesting and productive. If everyone in the Suzuki triangle really understands this definition, the battle of practice can turn into an interesting team effort." 

"If you have practiced and nothing has changed and gotten easier, it simply wasn't a good practice..." 

"Practicing is working on a small bit of a piece, usually very slowly, using many repetitions to make something easier..." 

"Each repetition is a chance to get that spot closer to the goal and easier and easier to reproduce more and more times in a row. If each repetition has a goal and can be evaluated for specific goals, repetition is not boring! It is fascinating and challenging." 

"Effective practice requires: finding the patters which occur throughout the piece and choosing places to practice them, and finding the small sections which are causing the stumbles, memory problems or technical difficulties."