Quote - ( blimey this isn't art, it's horrible science... )

There's an art to the science... or is that a science to the art?

Thanks Miss Nancy, for a concise breakdown of the other parameters to look at, I think.

While that brute force, no IC approach, can apparently deliver less artifacts, the cost in time can be significant.

I tend to go with upping the IDL bounces, IDL samples and pixel samples... and lowering the shading rate too.

However, in truth, I mostly render with at least one Infinite or Point light, bring the IDL Intensity down to 0.5 or below for exterior... maybe a little higher for interior, then go with between 4 and 16 IDL bounces, IDL samples 200, IC 42 or so, pixel samples 7 or 8 and shading rate of 0.4.

Relatively fast to render a straight forward-ish scene... and no splotchies generally.

I can still get red dot or black dot (not splotchies) artifacts sometimes, with that approach.

Sometimes that, separate issue, is the ray trace or IDL bounces being too low I think, also?