Well i have to say that it will depend on different kind of situations.
File size… Complex polysurfaces…and so one.
But as far i could understand with HOLO user, rhino shadows are a bit complicated than other softwares.
You have to read this article to understand why is it so complicated.
Nevertheless, we Rhino users just want perfect shadows, that work like other softwares (for me like sketchup), and work as fast and great accuracy no matter what. Specially if you work on rhino with “viewcapturetofile” PNG high resolutions output.
I think we need to wait for a new Rhino version with better tunning/tweaking shadows and OpenGL support as on CPU multiple core better improvement.
… but have you try to test the CLIPPING BUBBLE SHADOWS under the View displays modes options?
Try to fit the bubble to your project… I think i achieve better results when i made changes on that option. The bubble dont need to be huge or to small. Just the same size as your project… or in other way… Try to insert your project inside the bubble. And always draw your projects near the (0,0,0) coordinates.
Sorry i can not help better, but honestly i am on testing to. One think that i noticed is, no matter how i start, it will depend to much on the complexity of your model