Why does one have to wait six weeks to participate in auditing if one has been habitually using drugs?

WHY DOES ONE HAVE TO WAIT SIX WEEKS TO PARTICIPATE IN AUDITING IF ONE HAS BEEN HABITUALLY USING DRUGS?

Research has shown that it takes at least six weeks for the effect of drugs to wear off. Quite simply, auditing is not as effective while drugs are in the system because a person on drugs is less alert and may even be rendered stupid, blank, forgetful, delusive or irresponsible.