I’d like to begin with a disclaimer. I have done a lot of learning but very little of it has being about learning and so these rambling observations are simply my opinions based on a few years of watching other people and thinking about how they’re learning. Also, I’m going to use playing go for most of my examples - mostly because there are many learning approaches available and how much you’ve learned can be quite precisely measured.
There is a popular saying that practice makes perfect. I think it’s dangerously incorrect; I have seen people learn things extremely quickly with very little practice and other, smarter people keep practicing for hours a day and yet never get very far. Certainly time can help, but only if well spent - I think bad practice is far worse for you than no practice.