I check my some of my plants 2-18 times a day! If I find a aphid, I try to kill it on the spot. But the critters move around and trying to check 1,000 plants a day is not something I have time for. Safer Soap worked for a while, as did a pyrethrin spray. They can adapt to treatments - except being eaten.
Darn, I wish I could forget about organic growing - I have DDT in the closet!
Mike