Thanks for the help. Dialling up shadow offset starts creating all kinds of other shadow issues. But as earth quake said, this is simply not avoidable with ray tracing, as the rays use the low to cast shadow. I wonder why I haven't ever seen shadow issues like these in games with lower poly count.
I feel like my recent topology (hands) is suffering from this new found knowlege of shadow bias being a thing. Seemingly no retopology approaches I use that aren't getting to high poly, prevent the shadows from messing up when ray traced. I've also found that triangulating quads properly beforehand can help in some…