Hehe... Maybe in 20 years from now... :)
You are right, that is something, that would be just impossible. Or not impossible, but would make the work enormously slower, than how it should be. With every project we have a neat structure for the images that we have to create and we follow that with every part of the project. Also the scenes are split up according to that. So almost all the time every single image has their own scene in the end, so that way we can play with details and light for every shot. We than just use other parts from other scenes where it is necessary.
Of course this is not a strict rule, in the end it always depends on the specific project. But with bigger projects that's the case most of the time.