SetterGuy,
I used to have very hit and miss (mostly miss) with the rabbit call until my neighbor shared something with me. He told me that coyotes have a very good sense of distance and direction from their hearing. If a person calls too much, the coyote will know EXACTLY where the sound came from. He told me this. If a coyote hears the call once, it will have a good sense of the generally area from whence the call came but will not know precisely where. So he will investigate and search. The more a person calls, the more likely it is that the coyote will have pin pointed the caller's precise location and will be able to identify the caller before the caller spots the coyote. He told me to do this. Call once ... if there is a coyote in the neighborhood he will come into investigate. Give a coyote at least 15 minutes to come into view but wait no longer than 30 minutes. If no coyote, then assume none were close enough or hungry enough to come to the call and move to different spot or call it a day. He claimed that overcalling will ruin the hunt and educate coyotes. I had a lot of respect for him and followed his advice and although every hunt did not end in a kill ... a greater percentage did and I spent less time hunting.
Ill buy that, coyotes are extremely intelligent. Ive had more unsuccessful hunts then I have successful, I have always wondered about over calling.
I have a friend that hunts them at night with the thermal imaging scope, they are for one, not near as skittish after dark as they are thru the daytime. Quite a few people have started hunting them on a bright moonlit nite with snow on the ground with buckshot, its not uncommon for them to come a lot closer then they ever would in the daytime.
Friend of mine entered a tournament last yr where they had an entry fee and met up, and then everybody scattered in their own direction all nite and showed back up in the morning, with prizes for the most coyotes and biggest coyote, that was a lot of fun.