az native wrote: I don't know if it makes a difference, but the birds I hunt aren't pressured by other hunters.
That can and will make all the difference. Highly pressured birds that have been spooked by humans, called to and then shot at, often times develop lock jaw and won't gobble much once they leave the roost. If you're calling does elicit a gobble, pressured birds are are also more apt to respond with "courtesy gobbles", that is...I'm over here if you want to join us, but I'm not coming to you.
On the other hand, lonely un pressured birds without hens may readily respond and come running to a call. Of course there are exceptions to these circumstances, but on the whole, count yourself lucky!