Length of feeding...

My sons doctor keeps saying he should be feeding 10 or so minutes each breast every 3 hours...

AT MOST... he does 8 minutes on one side every 3 hours and I alternate each feeding. He pulls off and either falls asleep or acts milk drunk so I assume he’s full! He’s putting good weight on and sleeps and acts normal so I don’t see a problem with it. Maybe he’s a strong sucker?? My first son did the same thing! I have a strong flow. Maybe he’s getting more in one suck than normal?? How long are everyone’s feedings???