Tracking keeps it real
Studies have shown that most people think they are of above average intelligence, are better than average drivers and believe they will live longer than most of their friends of a similar age. What this tells us is that we are quite simply over optimistic. Tracking your practice will ensure you are not kidding yourself. This is important because it will ensure your expectations are realistic. One of the prime reasons I believe people quit guitar is because their expectations and reality are not aligned. They expect too much progress for too little practice.
Tracking helps your teacher help you
When you log your practice your teacher will have a much better idea of what to expect in terms of progress. If your progress is slow your teacher can look closer at your practice and make some changes. Small changes can often make big differences.
Tracking encourages us to do better
Many video games are designed for one player and the player is often motivated simply to beat their own high score. Most of those games would quickly lose their appeal if there was no score. Knowing our personal best (PB) compels us to do better. If you did 900 mins practice the first month you will want to do better the next month.
Tracking is the norm among the pros
In almost any profession whether it be sports, medicine, education, business or as a professional musician tracking is the norm. Olympic swimmers for example measure everything from stroke rates to blood sugar levels. They use state of the art pools with high-tech cameras to measure every part of their performance. When you are dealing with 1/100th of a second difference between gold and silver every little bit matters. While we don’t go to this extreme the practice log will make a significant difference.