Do you actually practice Excel outside of work, or are we all just learning on the fly?

I'm curious about how the rest of you approached mastering Excel. Do you actually spend your personal time outside of work practicing, building mock models, or studying formulas? Or do you just learn as you go when a task demands it?

To be honest, I think a bit of personal anxiety drives this question for me. I often feel like I'm not doing "enough" to stay sharp, even though I already consider myself an advanced user. But looking back, I realize I only reached this level because I had to solve specific, real-world problems on the job-- not because I sat down to practice in my free time.

Is "necessity" how most power users are made, or am I lagging behind by leaving Excel at the office once I'm out of the office by 3:30pm?

edit: typo