Never. Not even once. I don't even presoak when downstreaming, but I presoak, mid soak, 2nd mid soak, and rinse when I X-jet straight 12.5%. I carry two huge tarps, a few plastic drop cloths, and about 4 million spring clips for when it's mostly flowers.
I don't even know if my fear is warranted, but in my head flowers are a lot more sensitive than green shrubs and things like that.