If your goal is to have the absolute latest of all packages, then yes, that seems to cover all the bases. I'm surprised this has worked for you for a long time, though, because I would imagine you'd get bitten often by blocks, broken deps, etc. In the last couple years I've become much more careful about wholesale updating, electing instead to do it piecemeal after viewing the update tree. Gentoo development seems to have passed its heyday. Maybe it's because of the rise of Ubuntu.
Anyway, one additional thing you might try, just to be really fastidious about the whole process, is cleaning out your distfiles. There are scripts out there if you search.