The call doesn't make the stand more productive. There is no "this is the only way to do it" type of calling. There is no two people out there that sound exactly the same on the same call. the air is always introduced differently to the call, thus causing a different sound. Understanding where to hold your teeth or lips on the reed when attempting to make a given sound, is the fundamental part of it. When the fundamentals are takin care of, a person will then produce their own unique sound. The fundamentals are what leadbiscuit would be taught or encouraged at the minot hunt. when blowing on your open reed call, try to blow it by puffing your cheeks out and only your lungs. Try blowing from your diaphram (like single reed goose callers do). Try blowing with a little girggle from your voice. use your teeth versus your lips and vice versa. These all will produce a unique sounds in itself. I look at calling coyotes, a lot like calling turkeys when it comes to sounds. It has nothing to do with the "perfect" sound, but rather the tempo or rythm in which you make your sounds. I have listened to live hen turkeys that sounded like my newborn kicking my box call around the house. Listen to an old male coyote try to howl. There seems to be a lot of nasty girgly sounds coming out before the symphony starts playing. Same goes for rabbits and other game animals in distress. Their lung capacity plays the biggest role in which how often and how long they can scream in distress. Here is the order of importance to me on a stand.
Location - their has to be a coyote out there to call to or the rest wont matter.
wind direction - you don't want them smelling you as you walk into the stand
your set up - is the sun to your back, are you sky lined etc etc
your shooting - you can't kill it if you can't shoot
You calling - being on location with the right wind and set up will far outweigh your calling ability. So give it your best shot and sound like that rabbit whos nuts are in the process of being taken off with a spoon