I used to work at a company where running the full test suite took about 10min on my local machine. I would often run

    ./test.py; beep

where beep is a script I made that plays the Macintosh boot beep[1]. It was pretty useful.

I also did something similar that one time I had to compile LLVM (~4h on my laptop) and that other time I had to compile Firefox (~6h on same laptop).

[1]: https://ieks.cc/articles/mac-beep.html