Without having tried JJ, as a hype chaser, I can say it's both worth it and not worth it.

I run NixOS, work with Kubernetes, code Rust, use a 40% split, layered keyboard with Dvorak layout and open source firmware, kaj mi parolas Esperanton.

They're just hobbies that, once you've sunk the hours in, they're awesome.

I don't actually type faster. Or maybe I do type a little faster because it made me use all 12 fingers instead of the ad-hoc 7-finger system you taught yourself in primary school, but typing was never a bottleneck, and split keyboards actually hurt my wrists more.

Jujutsu is marginally better than git, but costs time. If you like to spend the time, it will probably make you a little better. If you care deeply about your time, and it's already being allocated for anything but arbitrary intellectual pursuit, it's not worth it. Some people grow businesses, plants, or sedentary habits.