How to cut rendering times in DAZ Studio

A interesting ‘taster’ video tutorial for DAZ Studio users, which claims to show you how to save 50% or more on your long render times (DAZ users can have 2-4 hours rendering per frame on complex scenes)…

Basically the formula seems to be something like this: render in layers (DAZ: “Render to New Layer”, with the DAZ Studio 3D bridge active to send it to Photoshop), each with a single light, stack the resulting layers, then use the layer blending modes in Photoshop to obtain your lighting effects. There’s apparently a free ebook on how to do this, at his — in exchange for your name and email address. I could be wrong, but it seems that this is a freebie that’s intended to get people interested in his paid tutorial courses?