If Progressive Render uses a different lightning model, maybe the light meter does not need to be changed. If you want to do the final render with Progressive, your should use the unmodified light meter, IMHO. If you use Progressive as a preview for the normal render style, you would probably need a changed light meter.

I found Progressive too blurry for my taste, also the results were different from what I've expected. I use it as a preview, but even then I do seperate preview renders before doing a final.

 

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

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