Understood. I know of people who have downloaded virtually everything available. As long as the system is large enough to hold the stuff that whould be fine.
What I have notived is, that PD will "in the background" fill the various rooms with the available (downloaded) features. It will also scan you disk for previous versions to ensure that stuff that was created and downloaded during those versions, will be made available too. THAT searching and filling process can take time too, depending on the capacity and speed of your system.
My basic position is that I only download those things I am going to use, knowing that if there something out there that I all of a sudden need, I can download it there and then without toomuch of a hassle.