Speaking from experience "this is what I've noticed" and others' experience "this is what I hear from others" the author lays down a foundation for how leading martial artists and professional athletes reached where they are, and believe that training for Mastery should look like. This is more of an opinion piece than a scientific study.
From where and why people give up along the way, to the common path most of these professionals followed.
- People often give up at the off-set. Usually this comes in one of three stages; When the original learning curve is over and things become hard, when they hit the a plateau in their progress, or when they have a drop in ability just before the next major jump.
- While putting time into it is critical, the path of Mastery takes more then time or effort - it takes effort over time. Thus, over-doing it may be just as negative as under-doing it.
Another aspect of the book is what the author calls "the war on Mastery", where he demonstrates that in today's society we are used to, and are indeed programmed to, seek the "quick fix", and the very concept of investing for the long-term being ridiculous.
It's a short book from the 1980s, freely available online. You don't have to read it all - but it will help you with perspective.