For MOST people - doing a parasite cleanse for 30 days every 6 months is enough. HOWEVER, there are people who are at greater risk for infection - ranchers, teachers, day care workers, international travelers etc. and these folks need to cleanse every 3 months (3 times per year). Waiting for at least 90 days between cleanses does assure that "super parasites" don't develop. This time limit is due to the life cycles of parasites.
Super parasites occur when certain herbs (at the wrong doses) are taken for too long or too short periods of time. If a resistant parasite infection should occur - the person must wait for 3-6 months and then do a powerful parasite cleanse - then wait 6 months before another one can be done. The person also has to take purifying herbs in between the parasite cleanses. Waiting while knowing you have parasites in your body is a very hard thing to do - but it must be done in order to fully remove them when the time comes.
HUMAWORM stands for "human wormer". Back in the old days, my grandmother made several wormers (among other things)-she made horse wormer, livestock wormer, pet wormer, and human wormer. Thank you for asking!