I think it's pretty obvious why I prefer to unzip a whole bunch of files at once. My zip file folder is about 25 gb strong, that's about 4000 single zipped files. It would took weeks to install then into the library one at a time. The content files from Poser are manageable that way, but I don't see why I should treat them diffently. 

Since I keep my runtimes stored on an external hard drive anyways, I can just plug the HD to another PC with Poser on it and start working. I don't think sharing runtimes via lan or even w-lan from a server would work, because of the amount of data traffic. But that's just me point of view, I don't have test this.