Each time she acquires a new Mac, she embarks on a week-long odyssey to set up her computing environment from scratch. It's not because she enjoys it; rather, it's a necessity because the built-in migration assistant just doesn't cut it for her specialised needs.
While she currently wields the power of an M1 Max MacBook Pro and runs on the Monterey operating system, she tends to stick with the pre-installed OS for the lifespan of her hardware, which often spans several years. In her case, this could be another 2-3 years or even more before she retires the machine or hands it over to a postdoc or student.
But why does she avoid the annual OS upgrades? It's simple. About a decade ago, every OS update would wreak havoc on her meticulously set-up environment. Paths would break, software would malfunction, and libraries that used to reside in one place mysteriously migrated to another. The headache and disruptions were just not worth it.
She decided to call it quits on annual OS upgrades roughly 7-8 years ago. While I've suggested Docker as a potential solution, it still requires her to take on the role of administrator and caretaker, which, in her busy world of astrophysical research, can be quite the distraction.
After several years of perennial macOS environment hell (part of which was spent working in a much more research-oriented environment - e.g. lots of ancient HPC packages, etc.), I made the jump to just using Nix on macOS [0]. Takes a little bit of learning (realistically just a couple hours to get productive IME - just enough to get acquainted with nix-shell [1] and build some configs). After a few months, I had the thought to look at what I still used brew for and realized I could just move to Nix completely - and remove Brew. I back up all my nix configs to a git repo, just in case - and whenever I switch to a new machine, or "brick" my current one - I just reinstall nix, pull in my configs, and I'm good to go - takes 5 minutes (a conservative estimate tbh). The only caveat is to just check the community [2] before upgrading to the next macOS version to make sure any issues have been ironed out. In the early days of macOS support, it was a bit finnicky between updates - I haven't had any issues for the last couple years that weren't my fault (for example, booting into recovery mode and accidentally deleting the nix store APFS volume - even then, all I had to do was reinstall nix and pull my configs).
It is so nice to just "declare" I want to use and just...use it. Want to try out ripgrep for something? `nix-shell -p ripgrep` Not what you want? just exit the shell. Too much unused crap taking up space in your Nix store? `nix-collect-garbage`.
There's even darwin-nix [3] as a sort-of "nixos-for-macos" - I started using it recently, mostly for managing macOS settings declaratively, and it's great - but honestly 99% of the usefulness I get on macOS from Nix is just using the package manager!
[0] https://nixos.org/download#nix-install-macos [1] https://nix.dev/tutorials/first-steps/declarative-shell [2] https://nixos.org/community/ [3] https://github.com/LnL7/nix-darwin