Somewhere along the way I lost interest in customizing the OS. These days I routinely switch between MacOS, Windows and various Linux flavors on lots of computers. The only thing I may customize is I write my .vimrc from memory.
On my Android phones, I change the wallpaper and I disable animations. Otherwise, stock everything.
Now that I think about it, it can't be the time saved, surely I waste more time on HN. It likely correlates more with using computers for work as opposed to for fun and learning. Even the learning I do these days is rather stressful - if I can steal an hour or two on the weekend, I feel lucky, so spending time to customize the environment seems like a waste.
Maybe if life slows down, I'll find joy in customizing my OSes again.