RE: gobble calls?
I have had luck with it in the past. Sometimes, when I have a gobbler that is gobbling his head off at me and is on the other side of a group of trees waiting for the "hen" to come to him, shake the gobble shaker and he starts to get a little more fired up and impatient because he thinks there is now another gobbler around.
I have a friend that lives in Washington (I am in Texas) who I consider to be one of the best turkeys hunters I know and he uses the shaker quite a bit, sometimes even as a locator-type call. I have tried it a couple of times in this manner, but I don't have near as much luck.
On an importance scale of 1 to 10, I would give the call a 3. I don't use it a whole lot, but it can work. One thing to remember, everytime you use the call, you might be attracting every hunter around your area because you are making a gobbling sound...so use the call with caution.