I do a 6 week break with either primo or anavar as a bridge when I have the cash. Right now I have been off for over 2 months, I should be starting up again in a month or so. For most people time on = time off.
Yes this is a good rule of thumb. Some guys think it's from the first shot till the last shot. Not taking into account the actuall clearing time of certaing drugs or counting post cycle therapy.
Also i must point out that the act of bridging is basically staying on all the time. When you bridge you no longer cycle. Simple as that. The act of bridging is a good indication of psychological addiction.