I used to fiddle with my vimrc, but then I got frustrated whenever I had to had to use vim without the complex setup, so I just learned to use vim with mostly defaults. I used to fiddle with my bashrc/zshrc, and then I used fish, which has most of the features I need anyway. I used to mess with global coding style configs, and now I just commit them to the relevant repo.
Maybe I'm getting old, but it's just not nearly as interesting as getting stuff done. The last time I messed with it was when I tried to get Rust spiffed out with the Rust Language Server, but I ended up not using it.
It feels like waste of time but occasionally it pays off after some time. And it gives myself some easily achievable satisfaction.
But on the other hand going for a walk would sometimes feel like better use of this time.
I have a quite small .emacs, and tiny user.js, .stumpwmrc, .bashrc and a few others. I think it's the way to go. Try to use as little software as possible, stuff that is well maintained, and don't fight its defaults too much.
In cases like emacs or vim, you do need some customization since they are trying to address such a wide userbase that their defaults are sometimes a bit odd, or just there for historical reasons and backward compatibility.