That must be "be careful what you "wish for" salvia! I have one Wendy and it's behaving, so far.
I took the plunge and whacked Henry and Augusta Duelberg nearly to the ground in early May, after posting question about cutting back. Henry is full and blooming again. Augusta is coming back more slowly. But I remember someone once told me, if I was going on vacation for 2 weeks, to cut the salvias way back before leaving. When we returned they'd but up and blooming again. Well, it took 3 weeks, but they did come back, fresh and not floppy...so far. They are located in the Hell Strip out by the street.