Most students make the mistake and waste countless amounts of time playing through versus practicing. They fail to realize that things need to be fixed or examined in smaller sections than what most students take on when "playing through".
A run-through/play through involves a larger unit and consists anywhere from 8 bars to an entire movement or piece. While run-throughs are necessary, by themselves, they are not a sufficient or productive way to practice and learn material. Run-throughs should take up less than half of the practice time.
The working unit, on the other hand, allows the pianist/student to focus and fully comprehend the material. Like phone numbers and clumping, the human brain can only fully comprehend so much material at a time. As such, the base of the working unit is usually 2 bars, sometimes 4 or 8, and always ends on the downbeat of the following bar. For example, a 2 bar working unit ends on the downbeat of bar 3. By practicing until the next downbeat, the pianist avoids the faux paux of ceaseless hesitations, strange rubatos when linking together complete phrases, the unnatural stopping-starting created by technical deficiencies.
