We have people who says it is conclusive and/or very good indication. If you want to help out on the forum great. Our advice has recently changed from 3 months to 8 week antibody test to 28 days for a DUO. But we are all volunteers here so if someone is more confortable with a longer time frame then so be it as we know it is still a standard.
Ok, Understand your point that as a general advice to someone would be 3 months, however if someon know he took a 4th generation test at 4-6 weeks it doesn't make sense to tell him (in this webpage) to take another test and not let the guy sleep letting him know his negative is conclusive
Also, the DUO test is most likely to pick up antigens around 27-30 days. After that it stands as a regular antibody test. And (very) rarely, there may be instances where neither can be picked up.
DUO tests are not available all over so if you only have access to an antibody test then the offical guideline is 3 months.
All experts here recommend the Duo at 28 days, Maybe about 7 months back they were not but now with new testing evidence 28 with the duo is the advise.