Animation prepass settings for Light Cache

[mohment]

I'm working on a large scale exterior animation with moving camera and objects and there are quite a lot of small details in the landscaping and architecture. I'm using the method laid out in the "Rendering an animation with moving objects II" on the spot3d site and I'm curious how to determine what the sample size should be for the light cache portion? I've set the scale to world and tried a small setting, .5 inches, but when I sent it to the render farm it was taking forever so I've canceled it and I'm sending it with a setting of 6 inches but its still taking forever. Do I have to use world scale? What is a good rule of thumb for this setting?

[bziegler]

I usualy use 10 to 15 cm with a scene modeled with real units.
But remenber that LC is used to help the IR pass.

At least it should be enought detailed if using it for Bluries !