Just had another look in KeyShot. The mouse wheel step value appears to be a percentage of the displayed value, and probably is a different factor depending on the function being controlled. For example, a random sample of three controls:

A value of 1 increments in 0.1 steps.
A value of 28 increments in 0.8 steps.
A value of 0.500 increments in 0.001 steps.

So again, a quick alternate way to edit values, and if set up correctly, useful to fine tune values without dragging or typing.

Ed