Interesting discussion to be sure. Please understand that any spray may (or may not) kill something IMMEDIATELY. Once critters come in contact with treated substances, they will likely die. The only questions are when and where. So, just because you may see something crawling, doesn't mean the product did not work.
FWIW, I received my graduate degree in Entomology from the University of Florida in 1979. Been doing this for many moons.