Earlier quoted context omitted.
Well, Linux is just kernel, and as such doesn't take so much time to build. A whole operating system (depending on what's in scope) would take hours or even days
Getting flashbacks to Gentoo building when I only had a single core. Good learning experience…
Building large software is consistently the only useful thing I can do that will fully utilize all CPU resources. Seeing all the bars in the red in htop on a box with a lot of threads doesn't get old.