It's easy if you remember the hotkeys, and since terraformed building placement became easy, even more so.
Pick any building -> press down LMB and hold for a while -> terraformed (up/down) building placement, use for skydust and buried singu
VX -> click on commander -> drag down for emergency save from assassination
VX -> Shift+Ctrl click on building = make wall around building (protect mex or moho)
VX -> Alt+drag = make square (e.g. large staging platform in a mountain, or nanofarm platform on acid throne, anything to fit multiple buildings, for individual buildings you can just hold LMB)
VX -> Ctrl+drag = make straight wall/trench
VZ -> click here -> click there = ramp (e.g. backdoor into enemy baes on ravaged, or a channel connecting two seas on that ugly supcom map)
I imagine you use hotkeys, modifier buttons such as shift, control even alt when otherwise ordering units around, etc, so it should be quite quick to pick up time-efficient terraforming if you actually tried.