Having set up CI for dozens of repositories, Nix and otherwise, I think I've stumbled upon some best practices. The following describes a pattern that includes all those practices.
The tool that manages your stress and workload: getting your work done, all of it, in time, and without stress!
The tool to get things out of your head to be dealt with appropriately for instant stress relief and to prevent future stress.
The most reliable tool to remind your future self of things from the past so you your present self doesn't have to.
Haskell project templates that save hours so you can start working on your brilliant business logic immediately.