First off, most people prefer recording the voices before filming, because it's easier to match the animation to voices than it is to match voices to animation. As far as sets, I'd imagine this is what most people will say: there's no need to build every set before you film. Especially when people big larger, more elaborate sets, it's not possible or practical to build all the sets beforehand. Personally, I'd say build a set, finish filming absolutely everything you could ever want to do with that set, then take it apart and use the pieces/baseplates for another set. Obviously, the problem with this is that you have to make sure that you will never need to use that set ever again, another reason why getting the voices beforehand is so important. I don't know about necessarily finishing all post-pro with the scene before destroying the set, but just make sure that you don't need to film anything else with that set. Always better to film too much, than not enough.