Why a fast and accurate evaluation?
If a person needs treatment, they do not need to run back and forth for several months for random drug screens.  They need to be in treatment immediately.  Treatment providers in Georgia can perform drug screens, and according the the Georgia Department of Behavioral Health rules and regulations, may re-evaluate a person who is in treatment.  The treatment provider can always step up, or step down the level of care / treatment.

An ethical evaluator will not keep a client running around drug testing while actually needing treatment.  It does not take multiple drug tests to determine what the level of care / treatment should be.  This is a very dangerous practice.  What if the person tested positive for a dangerous illegal drug everytime.  They probably should not be driving and probably should have already been in treatment.  It is not the evaluator's job to keep testing the person until the person tests negative for the drugs.  That is the job of the treatment provider.

On the other hand, a person may not need treatment at all, or only need "early" intervention.

If this is the case, an evaluator certainly should not require months of drug testing.  If the evaluator is properly trained, experienced and equipped with the proper diagnostic tools, then the evaluator can determine the client's needs appropriately without a long, drawn out drug testing process that may potentially put the client at more risk by allowing them to go untreated for months.