If by expert you mean someone better than 90% of all humanity at some task X, then the time to get to this level could be orders of magnitide smaller than a 95%, which itself is orders of magnitude smaller than 99.9% i.e. (pro/olympic athletes, concert pianists, etc).
If you don't agree please offer a counter example. Besides all sports, lets consider juggling. Here, 1-2 hours can make you better than about 80% of the population, but becoming a passable street juggler will take months, and a proffesional artists who can innovate as a juggler probably many years.
Essentially, my hypothesis is that improvements in a task X decrease exponentially over time.
Does it actually make sense to define an expert as skill relative to others? If I define my own programming language and am the only one that knows it, I'm inherently an expert in it by this definition. I'm better than |world population| - 1 people with this language. However, I may not actually be an expert. I could have created something beyond my ability to truly master (or that I haven't mastered to the level of expert yet).
If by expert you mean someone better than 90% of all humanity at some task X, then the time to get to this level could be orders of magnitide smaller than a 95%, which itself is orders of magnitude smaller than 99.9% i.e. (pro/olympic athletes, concert pianists, etc).
If you don't agree please offer a counter example. Besides all sports, lets consider juggling. Here, 1-2 hours can make you better than about 80% of the population, but becoming a passable street juggler will take months, and a proffesional artists who can innovate as a juggler probably many years.
Essentially, my hypothesis is that improvements in a task X decrease exponentially over time.