I've called a few w/coyote vocals, but not many over the years; guess I never learned to speak coyote. And like you, Bob, the coyote pup distress has a good record. I end most every stand with that, then sit a spell; have had quite a few respond to that one.
Only remember two that actually came all the way in to challenge howl. Have carried on a number of arguments w/mad coyotes, several that refused to cross a boundary fence, but would respond to every challenge I threw out. One in particular coyote ran up and down the roads running N>S and E>W (on the adjoining ranch side) barking and growling for 40+ minutes according to timer on my remote.
My partner was sitting tight in the corner and I was backed up in the bushes on the N>S fence line. He came up to the bush I was sitting in (thankfully impenetrable) and I thought he was gonna come through when I growled at him on one lap.
This picture taken at that corner on another day. Partner was sitting where my rifle is facing north), he covered the E>W fence and the pipeline sendero, I was sitting against the N>S fence facing north, covering that roadway. There is a cattle guard on the N>S fence right at that corner (to my partner's back) and the coyote was running back and forth, jumping cattle guard at the corner and travel about 40 yrds along both fences barking and carrying on, but would
not cross the fence. He would lose interest after a while and walk off toward the east, but when I challenged him, he'd come back to fence and take up where we left off. I finally tired of the game and let him walk on into brush on adjacent ranch. He was some worked up and I don't know how long he would have gone on had I not stopped calling.
This was a perfect example of territorial boundaries. I suspect that some of these territories pass from generation to generation, because all the years I hunted this ranch, I had several altercations in that corner and never got one to come across the fence when challenged. I did coax a number across at that location w/distress calls, however.