One could say I have a bit of an obsession with build times.

I believe having a "tight feedback loop" is extremely valuable: when I work on a large codebase, I want to be able to make small incremental changes and check very often that things are going as expected.

Especially if I'm working on a project that needs to move quickly: say, the product for an early-stage startup, or a side-project for which I only ever get to do 1-hour work bursts at most.