There are a lot of guys out there who like short cycles, but for this kind of cycle to be effective, the way things are done are a bit different. First off let me say that I do not like the idea of these kinds of cycles, they go against a lot of basic facts IMO. The biggest being homeostasis, which in terms of the human body refers to the bodies desire to remain the same. The object of training, diets, AAS cycles, is to eliminate the bodies ability to remain the same. But to do this adequate time is required, not short temporary changes or changes brought on by radical shock.
So why do people choose to run shorter cycles? Simple, these types of cycles can provide some very fast and radical gains, and I mean very fast, but maintaining these gains is virtually imposable because you haven't allowed the body time to adapt. You'll notice that I said that they "can" cause fast gains, not that it is a guarantee. The reasoning behind this is that some who run these cycles do so at a very, very high dose of the particular drugs they are using...that's the only way it will work...and I'm referring to doses higher then what any responsable user should ever use.
Many might argue that they see or know people who run these types of cycles with success and who maintain and keep their cycle gains. This is true, but there is one major key factor...these "success" stories never actually come off cycle. A lot of these guys use what is referred to as "bridging." Which means that in between their cycles they will run a lower dose of a particular drug. Any one with half a brain and understanding of AAS use can understand why this is a completely wrong approach.