I disagree, I think it's still possible to see good results/improvements through cramming etc; they just wont get the best possible results.
Going through the BOS summaries and finding the best/compact/relevent summaries and just reading them daily is prob the best thing to do if time is a constraint. Or you could try doing your own but just jump straight to summary of summary, e.g. Place emphasis on headings/subheadings/key points... I do this in my BS summary of summary and I think you can get alot of information using little text:
Chapter Heading
Sub-Headings (Syllabus names)
Under each sub-heading have lists of the main points