In the Incurable's Program, you rotate every other week D-Tox with Echinacea Plus. I am unaware of anything that says you can't take it all of the time, but would suggest that every other week isn't a bad protocol. If you want to take it for extended periods of time, I would suggest adding some milk thistle seed tincture to the regimine.
If it were me, I'd stick with the every other week rotation if I was feeling benefit from the formula. If I were feeling benefit, I would look towards doing a 30 day cleanse or the Incurables Program. :-)