Good Point Mark. My sister has a Cockapoo not even a year old. This dog literally flies. She is fast on her feet too. When she gets it in her mind that she wants out we haven't been able to stop her. Even using both the invisifence and a 4' chain link fence together doesn't stop her. Problem is she is moving so fast and launches at least 6 foot before she gets to the fence. She is poetry in motion when she jumps, clearing the 4' fence and landing several feet on the other side. She is already in the air before the collar even triggers and she is in the detection zone for such a short period of time unless we turn the system to max sensitivity it doesn't even fire.
I do have to say though. I never knew a dog could do a backflip while sailing in the air from a full run, land on her feet then pick-up speed with a yep from the zap. It was like a jet fighter lit it's afterburners. LOL