It might be 10,000 hours spread over several lives. Tendencies, skills and talents are carried from one life to another. This is how you get Mozart composing music at age four. Does anyone think that of the 35,000 hours he had been alive, 10,000 of them had already been spent composing music? When I was three, I didn't know how to read. When I was four, I could read at a grade 6 level. When I was five, I could read at an adult level. It wasn't hours of application, it just came to me after I was shown how to read once.
One day when I was four years old, our next door neighbour was painting the trim around the basement windows. I told her I could read. She gave me that "yeah, sure" dismissive look and said, "OK, read the paint can if you can read."
I started off, "Exterior enamel. Make sure all surfaces to be painted are clean and dry..." and I could read it at an adult level with no hesitation or sounding out of words. She ran off in terror! Her son was two months older than me and could barely read anything. Was this application on my part? Not in the least - I was noteworthy for my laziness at the time (and some would say nothing has changed).
You start your life with tendencies like patience, extroversion and other such characteristics and quirks but also the accumulated sum of the things you knew how to do previously. There was a theory called "Tabula Rasa" meaning "blank slate" meaning each infant starts life knowing nothing and begins to differentiate himself only after experiences in this life. Pediatric nurses never believed this and in the past five decades or so, medical doctors have realized that people are born different and diverge from there. Of course, Tabula Rasa was one of the best episodes of Season 6 on Buffy.
This also accounts for the sense of deja vu that people get in some places. A colleague of mine (also an engineer) was touring Greece and was wandering through an old amphitheatre and before he went into each room, he knew what he was going to see. But since he is 6' tall, he kept bumping his head on the door lintels. He knew he had been there.
It also accounts for love at first sight. When this happens, the people involved were together in another life. The first time I saw my wife I hadn't had a girlfriend in several years but I immediately thought. so this is how the drought is going to end. There was no reason for me to think a beautiful girl four inches taller than me would be the slightest bit interested and I was usually not confident in social situations, but with her, I had no problem and I asked her out for a date the day we met. She agreed because we had known each other before. The rest is history.
If you have spent time learning an art or skill, this time and the lessons learned will be carried into future lives. If you have a talent but fail to develop it, it will dissipate. The music lessons that you really had trouble with in this life will be things you "just know" in the next life. The painting techniques you learned in this life but seemed to never get right will be second nature in a future life. So don't worry about your lack of accomplishment - it is just preparation for the future.