Yes, I use the tape method,...but no graph paper, although that is a great idea in terms of getting the reed stretch as close as you can to the same every time. I also tape each reed separately so I can vary the tension to see how that impacts sound. Obviously, that adds another factor into the call-making process that complicates matters a tad.
Because of all the variables in call construction, my methodology focuses more on adjusting the sound of each call with the reed cutting process. I have found there are lots of little things in doing that the impact the sound of every call. Pretty much every call has a turkey in there somewhere. It's just a matter of finding it.
