There's another reason why a shadow setting of anything other than 100 is wrong (not necessarily unusable - just plain wrong).

The above scene is lit by one radial light. The sky is black, and there are no walls to provide any bounced light. No light falls behind the block because the block is opaque and the only light in the scene can't get there. There's a beach ball behind the block, but you can't see it because it's in a totally dark shadow.

Bryce renders this correctly because the shadow level is set to maximum - 100.