Malcolm Gladwell’s Outliers covers, among other things, the “10,000 hours” rule of success.  Simply put, it suggests that we master a craft after about 10,000 hours of practice.

I want to be a solid writer, but I only have about two hours a day at the most I can commit to writing.  So if I write two hours a day every day, I will master the craft of writing sometime in 2023.