i had the same feeling when i just got the aquaracer chronograph, even my old mido keep better time that it. running at +-20s and if its in watch winder probably more than a min. i concluded that my mido has higher end ETA than tag's valjoux. End of day i treat it as a fashion watch cause its does look good on my wrist
Right until i gotten my iwc chrono pilot, even it doesnt mention cosc, it keep excellent time +-3s second per day. So end of day i given up comparing to atomic time and just enjoy wearing watches.