I don't know about the "3 weeks" thing, but it seems to be well tailored to sailing. I do a bit of gym work, but I've never met a gym instructor who had the faintest idea how to train for sailing these sort of boats, so I found it pretty useful. I think most of it could actually be done with nothing more than a flat bit of floor and maybe a couple of dumbells or a medicine ball.
I, believe it or not did three years of sports physiology at Uni some time in the past and have been working on a fitness program for sailing with a personal trainer. I would be happy to put together some ideas and some articles I have collected over the last few months if people are interested. Blackburns book is really excellent and well worth the purchase price if sailing fitness is a goal. However it will not ensure being able to duck at the appropriate time.