If a person had 6 microbrews... 14 ounces at 6% alc... if a test needed need to be run at 7pm Tuesday... bac was zero at 12 noon Saturday... 185 pounds-male... Stopped at 12 Friday night... so 91 hours from last drink... if you are out there Dr Bill? What do you think of scenario

Drinking water and working out, does that reduce the hours of EtG in your body?

At that level of consumption (8.4 drinks (US)) there is no record of EtG detection at or near the 90 hour range. No heroic efforts are required.

Also, your rate of consumption (across 12 hrs) greatly reduced BAC and influenced metabolism.

You should have reached BAC=0 long before noon Saturday?

Does the 80 hour test usually refer to the last drink or when the bac is zero?
I realize most of the studies show that the 80 hours is rarely the case... what would your guess that the EtG in the above example gets below 100ng... from sat 12 noon? In hours?

BAC.. was measured then.. not sure actual... drinking episode was over 7 hours (if that matters)

There is no standard for the time span. It is necessary to review the methods of each study to determine baseline. Some use first drink, some last drink, some measured BAC, some estimated BAC and some rely on BAC only with no knowledge of amount consumed. The research is extremely disarticulate.

Information is not available to time EtG/EtS with even a semblance of precision. It is widely variant between individuals. It is probably also related to concentration of alcohol in system (beer is low, whiskey high). In addition EtG begins with the first drink and peaks about 3 hours after alcohol then begins eliminating. So, rate of consumption plays a role, that is time from first drink until last.

Following that idea, after last drink you could have been EtG clear anywhere between 24 - 70 hours.