Adjustment Field Increments w/Cursor Keys?

[paulbk]

Can someone explain the logic, or lack of, behind adjustment increments using cursor keys (up & down arrows).

re: Develop Module Adjustements
I like to click in the number field and use the up & down arrow keys when making adjustments. However, it appears that I can not get the same precision as in Photoshop. (i.e., small increments that I can more or less anticipate) Sometimes the increments are in units of 5, other times in decimal increments. And some times the number turns Red? Not out of bounds, it just turns Red.

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