This experimentation has resulted in an understanding of what these manipulations can produce, and personal preferences in regard to what works best. These days, however, such exercises usually are not necessary. All calls mass-produced by a manufacturer may not sound exactly alike, but they should be close. Perhaps we have all left calls overnight in our vehicles, or in the blind, at one time or another. Howard Harlan says that's one of the worst moves duck hunters can make.
Duck hunting is done in the wintertime.
My point is, this is an instrument into which you are putting moisture. If a wooden call gets cold overnight, down to freezing, that call is going to expand, and it just might break. Take your call inside with you. Dry it out. Calls can be tuned, but keep in mind that almost all double-reed calls are put together with a wedge that is stacked on top of the tone channel.