I have generally used an ECA for only a month or so at a time. I get the results I'm looking for in this amount of time, but I lose sleep when on an ECA, so I personally have no interest in going more than one to one and a half months on it. A solid amount of sleep is necessary for proper recovery, so detrimental effects to sleep should be considered. I, however, would find it interesting to see if anyone has any research regarding the health effects of a prolonged cycle.
cookmic5