No, she's right- particlized sulfur'll rinse right off. Hopefully, though, what remains will suffice to inhibit fungal growth.

Same thing w/ the subtillus ( Serenade) - most of yer subtillis will dislodge, but enough remains to have a colonization advantage through raw #s over whatever fungal pathogens show up. The same conditions that'll grow mold will grow subtillus- and if you've already introduced about a bazzilion individuals, you've stacked the deck pretty heavily.

With the subtillus, the reapplications are mostly to keep the colony alive when things dry out.

Outside, this time o' year- I'd be spraying serenade every time the weather said it was going to rain, if I had the access.