My latest 3 runs have all gotten 5 extra minutes added to total time. They were all structured workouts from Trainingpeaks with 45, 53 and 45 minutes duration and did in fact take that long. The watch, however, reported 50, 58 and 50 minutes. GC and Trainingpeaks reports 50, 58 and 50 minutes but Strava and Stryd reports 45, 53 and 45 minutes after sync. There is probably something weird in the fit file.