It is a total waste of time. Seat Son paid $145 and waited some hours to get a paid PCR about 60 hours prior to his return to UAE. He got his results back pretty quickly - about 8-9 hours - negative for COVID. Then he went out with his mates that night and the next night we had a family farewell dinner for him. One of the family members and her boyfriend both tested positive 36 hours after that dinner. By then Seat Son was on the plane home off the strength of his (now very dated) negative PCR.
It's just a stupid waste of time, money and resources that could be better directed to other uses. His test was an airline and UAE entry requirement. I suppose it would have stopped him if he was positive at the time of taking the test, but there was plenty of time and opportunity for him to get positive in the intervening period before his flight departed. If airlines and countries think a negative PCR is preventing positive people entering their flights/country, they are sadly mistaken.
BTW, looks like vaccine and boosters did their job, because no one at the dinner caught COVID from the 2 infected guests, including Seat Son (triple vaxxed), my elderly mum (triple vaxxed), 15 month old unvaxxed granddaughter and everyone else double vaxxed (not booster eligible at that time).