At one time, I recall someone having made a list of the most efficient way to install store content if you owned most of it, without duplicating it, but I can't find the link now. If anyone knows what I am talking about and could link it, I would be thrilled as I couldn't find it in a forum search.
Comments
http://forum.thesims3.com/jforum/posts/list/699319.page
Hope this is what you were looking for
Happy Simming!
Edit: Oh and also this list was last updated 02/01/14 so there will be the more recent sets etc to add to this.