My theory on how often I calll an area is based on growing up going with my dad hunting with greyhounds. If the area has the right cover and you kill the coyotes you calll go back within a week another coyote may have moved in.
I have called spots that didn't produce, go back in a couple days and connect. Coyotes travel you never know when one maybe in the area.
I have lots of area to hunt but I will still call some of my better spots 10-12 times in a 3-4 month period. Changing up where I call from and how I call and length of time on a stand.
I have a spot I call my honey hole it is a travel way from a large creek to a lake. It's a 2 mile section. A few years ago I took 13 coyotes out of this place in a 4 month period. This year I have Called it 4 times and have not seen a coyote, but I will still call it every week or so for the next couple month.
You never know when or where a coyote may be. I have called them out of waterways, overgrown fence lines, hedge rows, weed covered washout in the middle of wheat field no bigger than a pickup truck. If you don't educate them there is always another looking to move in, be there with a house warming gift of lead.
Here is an area I call that produces from 5-10 a year, this year 2 coyotes and a cat so far.
Both coyotes were called from the red circled area. That over grown water way has been good to me for the last five years. I will call from some where in this area every week and sometimes twice.