"so I don't know if it makes sense for one company to license one patent without the others"

It does make sense. As an example, of the 3 patents listed as the main patents on the ptsc website, patent 5,784,584 (multiple instruction) does not depend on patent 5,809,336 (separate cpu and io clocks). Therefore it is possible for a company to infringe on just one or few of the patents and not all of them.