Hi, I use meta-mode in /etc/src-env.conf so that if (for example) a small change in the kernel config is made, the machine doesn't take hours recompiling.
Also, (I *think* it works this way) if src gets updated by git and world/kernel rebuilt it won't recompile already compiled files provided I don't delete /usr/obj/* But, from time to time, one might be required to make cleanworld && make cleandir (to be sure) && make clean (to be *really* sure) What circumstances & notices in /usr/src/UPDATING would require it? --