I used Yocto/Bitbake at an old job where they needed to make a custom distro for a bespoke device that went into extremely large vehicles. IIRC the biggest hit for rebuild speed involved certain settings that had ripple-effects across many different recipes or artifacts.

It was challenging since I somehow got saddled with babysitting the system (despite having no C/C++ experience) as the team gradually broke apart for other projects. I was probably too amiable, I need to move more towards the "give me a cool sexy project or I walk" end of the spectrum.