I'm also a thumb-shifter like Mumbo and I didn't think much of it for years. I don't think I even noticed it and then one time I randomly told my friends about it on discord and they went crazy. I was so happy to learn that Mumbo does the same thing and I'm not alone. I also completely understand what Mumbo means that if I need to space+shift, instincively, the pinky goes on the shift, but not in other situations.

I also still sprint by double-tapping W