Warren in Lancaster, PA
I think I have seen, even used, pit saws that had graduated teeth from end to end. A saw that has many teeth in the cut can get into a harmonic vibration. The inside of the cut gets to be sort of a washboard and the saw chatters because all the teeth hit the washboard humps at the same time. A saw with graduated teeth would not have that problem.

The word pitch usually denotes an angle, not a spacing. In older texts pitch is used for the rake of a tooth, as in "common pitch".