RE: Hort oils
To a degree, I agree with you about the level of "usefulness" of HORT OILS. In general, they're intended to control scale, certain gall insects (i.e. adelgids), and some mites. I have found that I can get reasonable control of some types of scale. (Although it may take 2 apps in the spring to achieve this control.) Spruce adelgids?? The oil sprays fail to make critical contact, and the galls form anyway! Good coverage is essential; yet at the same time you increase the chance of "oil burning" spruces. As for mite control with oil. I don't see it.
In the end I think that hort oils are generally used by the big revenue companys as their Round 1; to get out the door first thing in the early spring when temps get into the 30's!!!