Musicians, like golfers, have to put their minds in the right place – trusting, confident, enjoying the pressure, being in present. And so forth. Otherwise, no amount of practice or “Time management” will make them better. The same is true in all professions: if you’re stuck in the Training Mindset, evaluating yourself, or thinking in the past or future, you will not perform up to your potential. You will waste a lot of time, be an inefficient performer, and likely assume you need to manage your time better. In reality you need to manage your thinking better. 
John Eliot, Overachievement: The New Science of Working Less to Accomplish More
eliot, inspirational, overachievement, time-management