As Brokenbucket stated, a lot of public birds are hammered with owl calls in the morning and crow calls in the evening. My success has been 50-50 with owl calls and less than that with crow calls. I tend to not use them at all until I'm desperate to locate a tom. My loud box call tends to get a distant tom to respond better than anything else.

I do remember back in Wisconsin when I hunted a lot of logging roads, we used to slam our vehicle doors shut and get a response! Another time I located a tom shock gobbling when an Airforce Jet flew over.