In theory Hair Alcohol Testing (HAT) could detect a one time use of six drinks. I doubt that it would. There are several types of HAT tests. One looks for EtG in hair. Another looks for EtG and FAEE and yet another for EtG/EtS and FAEE.

EtG has a history of being detectable only in regular (not infrequent) drinkers and, even then, is greatly reduced by regular hair washing. The metabolite EtS is produced in smaller quantity than EtG and usually not detected in moderate drinkers. FAEEs usually rise above the level of detection after the consumption of 7 or more drinks within the period of a week. NOTE: I am using the standard for a drink being 1.5 oz of liquor, 12 oz of 5% beer or 5 oz of wine. In real life, beer is about the only beverage containing a standardized amount of alcohol per drink. Poured drinks may be more or less than the standard.

Generally, in the US HAT is looking for EtG in most cases. The UK has now adopted the dual EtG/FAEE test.