I agree … and design consistency would address this problem.
With global adjustments, slider values can be adjusted using the cursor keys (up, down, left, right) - if this behaviour was the same for local adjustments then it would be easy to fine-tune adjustment values.
You can vote for this here … 10 votes already there, as of now.
Yes, that’s sort of true, Mark … but I still don’t find it easy to make “fine” adjustments - and esp. not to the degree referred to in @man’s example (above).
And, regardless - - UI consistency should be a design priority.