That's what I usually do, except that in some cases it isn't possible to render in layers: Because of reflections on other objects, because of shadows of some objects affecting light conditions on other objects, and/or because actually a couple figures are imbricated, like people inside a car for instance, with glass transparence/reflection and car shadows affecting them.

In this specific scene all I could easily remove is the skydome, but I don't expect it will change much since it doesn't even have a texture. As for the figures, they are inside the vegetation, and if I have to spend hours in Postwork drawing stencils and faking shadows, it isn't worth it; I'll try rendering in Vue (but it's a pain, because, as I said, most textures are Poser procedurals).

Actually most of my scenes are too heavy for Poser, despite me losing a lot of time improving memory usage.  :-(

Apparently Poser is only good for rendering NVIATMAS: Render naked Vicky with her sword, paste on pic of temple, no memory problem.  :-/