Approximate etg times

EtG tests provide an accurate and reliable indication of alcohol ingestion within the previous 3 to 4 days

There is really no answer to your question. Averaging the various studies isn't possible because of the methods employed in each. Most of the information you read is based on one study, the one most favorable to the author. So the commercial testing field has used the 80 hour test. That time span applies in only the most extreme cases. It is not an average.

EtG production and elimination is highly variable between individuals and even within the same individual from time to time. The window for detection is also dependent on the amount of alcohol consumed. It is dose dependent. EtG created from one drink is eliminated faster than 10 drinks, a small amount faster than a larger amount. This follows the standard elimination curve of ethanol (EtOH) metabolism but at a slower rate. EtG is the waste product of the metabolism and proportional to systemic EtOH.

Here a few studies dealing with detection time using measured doses:

9 drinks (Borucki, 2005) 100% positive at 24 hrs, 77% at 54 hrs, 18% at 78 hr.
3-5 drinks (Sensitivity of commercial ethyl glucuronide (ETG) testing in screening for alcohol abstinence ? Alcohol Alcohol) none detectable past 48 hr

To provide you with an overall concept of elimination time in a small sample (see P. 597, Figure 5, Rosano & Lin, 2008) This is a time scale graph.

The research data on EtG is very limited. There have been no large scale studies and there is much more to be learned.

A good resource for additional information on EtG and EtS is Dr. Greg Skipper website. He introduced the test to the US and does a reasonably good job of providing current information.

So if you drank 5 out of 7 days the etg from the first days of drinking burns off as the days pass even if you drink more alcohol? I guess my question is if the 3-4 days means all alcohol will be gone from your system after your BAC goes to 0 on the last day of drinking instead of etg building up over the days of drinking and not starting to metabolize until you stop drinking on the last day? Been clean 6.5 days so I am assuming I will be free of alcohol regardless.

Yep, most definitely.

Tick

It follows the same curve as EtOH metabolism. It is being metabolized as you drink just like the alcohol. EtG is not cumulative in the sense you mention. If you have consumed no alcohol for 6 days you have no residual EtG in your system now.