as I understand it, the ideal way to do it is 10-12 weeks on, and then an equal amount of time off.
on the other hand, I can't do that, I don't have the willpower to be 10-12 weeks off, so I bridge and take less time off as well.
there are many people that stay on all of the time, the main disadvantage to it (from what I've heard mentioned here before when this same thread came up many other times) was that your liver builds up a tolerance to the gear and you need more of it to ge tthe same results.