Shutdown is one of the major sides of running cycles. So this is why I disagree with the 2 wk cycle, not saying it cannot work. I would rather see you go eod with 3x a wk dosing and run it for much longer than put your body at risk for shutdown, extending the cycle and making slower more managable gains... hence the whole backbone idea behind pulsing. But there are always more than one way to skin a cat.
Well, if you want to avoid shut down COMPLETELY, then yes, I guess your only option is to pulse and cross your fingers. However, with the 2-week protocol, if done correctly, by the beginning of the second "off" week you are typically already recovered. In fact, people who run it report continuing their gains during the off weeks as well. This is great because it allows you to carry your gains to the next 2-week "on" period instead of having to play catchup and re-make gains that were lost during PCT (which is what most people are used to). So while technically you would be shutdown, you wouldn't experience the "PCT crash" commonly associated with cycles that are 3-12+ weeks long. This is a huge advantage in my opinion, as going through the "PCT crash" myself sucked.
And as for how many "on" cycles you can do in a row, most people seem to to 2-on/2-off three times, and then extend the third "off period" to 4-6 weeks, and then repeat.
If you guys are really interested you should check out this thread:
http://tnation.tmuscle.com/free_online_forum/sports_training_performance_bodybuilding_gear/2_weeker_1
There are some great links in the first reply as well as an informative discussion with Bill Roberts himself (the guy who developed the protocol).
Also, here is a 2-week protocol "case study". You can also find the bloodwork and see that the guy's hormone levels were back to normal very quick. I do want to mention that some of the aspects of the protocol have changed since that article was written, but if you check out the other links I posted you'll see what I mean.
http://www.mesomorphosis.com/articles/pharmacology/steroid-case-study-01.htm
The key to rapid recovery is explained by Bill here:
The advantage is that there's actually a two-stage process of inhibition. You have the hypothalamus and the pituitary. Between the two of them, the hypothalamus produces a hormone called LHRH, and that tells the pituitary to produce LH. LH tells the testicles to produce testosterone. Now, after two weeks, the pituitary actually isn't inhibited yet. In fact, it's sensitized. So it will put out more LH from LHRH during the first two weeks. If you stop at two weeks, the recovery is very, very fast. All you have to do is stop and when the hypothalamus produces LHRH, you're back in business, especially if you use Clomid. You'll get a very fast recovery. You'll be back to normal in less than a week. But, if you go beyond that two-week point, the pituitary also goes into a state of suppression. And from that point, it can take many weeks to get back to normal.
Now you can see that once you go past the 2 week mark, you lose the main advantage of rapid recovery. This is why I don't agree with 3-4 week cycles either, you might as well go 6-10 weeks (obviously not orals-only). Also, I'm convinced that pretty quick into a cycle your body starts to "fight back" in an attempt to reach homeostasis, which is why gains begin to taper off. In "Building the perfect Beast" by L. Rea, I think he makes the case that this starts to happen about three weeks in. Therefore, I think the 2-week protocol allows you to get, make some gains before your body can adapt, and get out. Something I think is important for us to consider is maximizing the efficiency of the time you spend "on" per year - it's a well known fact that the longer a cycle becomes the less efficient it becomes as well.
So yes, if you want to avoid shutdown completely, your only choice is to "pulse". If you want to make the biggest changes to your body possible between now and 6-10 weeks from now, then you should run a 6-10 week cycle. However, if you are fine with "slow and steady gains" and more concerned about long-term gains (over 6-12 months), and want to minimize the side effects during the process, I think the 2-week protocol might be for you.