I set up a new laptop this week and spent the first hour reconstructing my shell from memory, which is the sort of thing you only tolerate until you have done it three times. My .zshrc was a fossil record of every machine I had ever owned, with half the aliases pointing at paths that no longer existed.
So I did the obvious thing I had been putting off: one repo, version controlled, symlinked into place with stow. Each tool gets its own directory, stow zsh drops the symlinks where they belong, and git tells me exactly what I changed and when. No more copying a file between machines and wondering which copy is the real one.
The bit that actually saved time was a tiny install.sh that runs stow for each package and installs the handful of tools I always want. A fresh box is now a clone and one script. It is not clever, and there are far fancier setups out there with templating and secrets management, but mine fits in my head and it works. That is the whole point of dotfiles, really: the machine should feel like yours within minutes, not by the end of the day.