Gotta think about this one for a moment.
I did like to draw and doodle quite a bit growing up. I also took some art classes in high school and college, but I'm not an artist by trade and hadn't really drawn anything since then until I started to make tiddy games. It's especially apparent on some of the early artwork on Grolokk.
I've been working on Grolokk for over two years. Inbetween making actual content for the game, I've watched quite a few drawing tutorials on youtube. Practicing fundamentals, like perspective, figure drawing, color theory, etc. I try (often unsuccessfully) to draw in a sketchbook at least once a day.
Shooting from the hip (a rough guess), I'd say between two to three thousand hours of practice, lessons, and creating content to get where I am now.