My base 1 and 2 both had tempo work in it in increasing amounts. Base 3 included sub-threshold (SST) work too. It all depends on who's plans you follow. I follow Friel and this was it. Also did several cycles of Base 3 before moving to Build 1.
Around here, if you just stay in Z2, you'll never get up the hills anyway. I like to think of it as going 'mostly easy' in the beginning. YMMV.