If you are using it correctly, it is a foliar spray. It should not be dripping off onto the soil. The hotter the day the better it works.
This stuff will kill many plants and will not even touch some others. You will have to experiment. I have used my homemade recipe stuff on oxalis in my St Augustine lawn, on patches of bermuda, and English ivy.
My results: Oxalis dessicates completely in 4 hours. St Augustine overspray dessicates in 2 days. Bermuda turns brown in one day and turns green again in about 2 weeks. The English ivy was not affected at all.
Others have reported quick dessication of poison oak and ivy. Retreatment at least one time was needed to take it out.
Manufacturer's website (not much info)
Reseller's website (better info)
Front of BurnOut label in pdf format
Back of BurnOut label in pdf format
MSDS for BurnOut
You will also need to flush your sprayer with fresh water immediately if it has any metal parts in it.