Given the new info in the comments, and ruling out whatever mouse is currently used as having software that would acceptably modify scroll wheel threshold sensitivity, I can only recommend Autohotkey to assist here.
Speed = 1 WheelUp::MouseClick, WheelUp,, , %Speed% WheelDown::MouseClick, WheelDown,, , %Speed%
AHK's documentation isn't the best, so while they suggest speed progresses from 0 (fastest) to 100 (slowest), I find the reverse, where 1 is fastest, and 100 is slowest, so I suggest experimenting to see which works.