GTD promotes a bucket named Read/Review. It contains all material that should be read or reviewed. There is one problem with this label : reviewing is reading.
All reading material not yet sorted goes into that bucket. The stuff that will matter after being read should go into reference material. There is one problem with this process : sometimes, reading material should go directly in the folder of the project where it is needed.
If we have both reference material and project material, the complexity of finding back reading stuff increases. The ideal solution would be to decide between the two ways of sorting. There is one problem with this idea : most of reference material is too general to fit into one project.
The read/review bucket is not tight enough for the basic needs of intellectual work. One needs a bucket for review ; one also needs a bucket for reference. The reader should always ask himself : is my reading good to know or good to use ?