I keep reading the claim that if one reads in one's field an hour a day for seven years, one will become an international expert in the field. (I keep reading it all over the place, but I don't know where it originated, so I'm not linking. I'm guessing you've either read it or heard it or could find it with a quick internet search if you look.)
I call BS.
First, it's only 2555 hours. That doesn't get close to Malcolm Gladwell's mythical, minimally supported 10,000 hours to become an expert.
Let's think about, say, grad school. Say someone who's thinking about grad school starts in their junior year of a traditional undergrad program and starts reading, say, literature in English. They average an hour a day reading, more if you count time in class. Certainly, if they're taking 9 credits of lit courses each semester (assuming a semester system), that's, say, 18 hours a week reading and/or discussing, minimally. Even if they don't read much over the summer, they're still doing the hour average.
Then they start grad school, where they'd better be reading more than an hour a day. And they spend five years in grad school.
So there's seven years, reading more than an hour a day. And you know what we call that person? A grad student, a beginning expert. Sure, they know tons. But compared to people who've been doing work in the field for 20 more years, not international experts.
Second, to become an international expert, one doesn't simply read about or learn about a field, one contributes. One gets challenged by other experts at conferences, in papers, in classes, seminars, conversations, and one thinks harder and says something interesting and new.
On the other hand, if you spend 2555 hours learning about something, you're going to learn a whole lot about it, aren't you? So there's that. You may not be an international expert, but hopefully you're using your knowledge to make helpful contributions.
I don't usually practice an hour a day on my violin. Usually, it's more like 40 minutes or so before my arms are tired and I get sloppy in that tired way, and my practicing loses focus and becomes less useful.
I've now been at it 12 weeks, and yesterday, I had a tiny breakthrough. I've been playing this piece from the Suzuki book, "Perpetual Motion," which is hard (for me) and at my level includes practicing a lot of "crossings" which are when you change from one string to another.
My tiny breakthrough involved being able to play it better yesterday than I had before, and in three different keys.
At the most basic level, I'm beginning to "get" how violinists can switch between certain keys so much more easily than I ever could when I played wind instruments as a kid. If you start on an open A string, and do a basic A scale, you're in A. You can learn songs (the intro Suzuki songs so far are mostly in A). And then you can do the same basic stuff (same finger positions, same bowings) on the G or D string, and you're in G or D. (I'm totally thinking it's way harder when you move into other hand positions or other keys.)
I don't think 2555 hours of violin is going to make me an expert. It will, I hope, make me a whole lot better than I currently am. But not an expert.