I track time spent on my hobbies. First I hated the idea. I saw it as self-surveillance, as an intrusion of accounting and management in my personal space where precisely, you don't count your time.
After two months I realized I had the wrong feeling. Tracking hours has become a tool for self-discovery. It allows me to take a huge step back and to be more careful about my well-being. It also helps making connections between what I do and what I feel every day.
For example, for the first two months of 2020 I spent around 70 hours on personal projects. It's 7.8 hours a week, which means I overall worked a day more each week on personal stuff. It made me realize I was on the wrong path to accomplish one of my goals, which is to be less productive and more creative.
For people like me who wonders where their free time disappears, tracking time helps. My advice however, is to find a personal way of tracking time instead of using apps, bullet journals or stuff related to productivity. Finding your own way of tracking your own time is also part of the self-discovery thing.
To me tracking time doesn't mean trying to be more productive, but the opposite.