Aound here they only bloom once because no one bothers to do anything with them. It could be self-defence on the part of the gardeners there - My biggest weed nuisance (other than cheat grass) is Russian Sage. Your gardeners don't feel like pulling all those baby Russian Sages next spring.
The RS should be cut back after they go dormant. Otherwise, all that dead stuff is still there amongst the new growth. Around here, they are really a nuisance plant. Idaho has outlawed them and put a bounty on the ones that are wild in the desert.