The more you call, the more likely the tom will notice that you've got a funny accent and you don't use quite the right words.
I've noticed this as well and have more problems hunting Southern turkeys. Seriously, I have a favorite call that has given me good results and then, nothing and it seem they are speaking a different language. ....
Last year that happened to me and decided to switch calls by going to a gobble and the woods came alive !!!
Be Safe !!!