I don't think amount of time he feeds for matters. As I understood it (I'm down to 1 feed a day with my 13 month old), the baby gets more efficient at extracting the milk as they get bigger, so could be getting more from each feed as he gets a more effective suck. My friend's DD was a 5 minute feeder, always, and would go 5 hours on that at night!
I was stuck with a frequent feed pattern with my DD of every 2 hours at night, though she would go loonger in the day. In the end, the HV and mw's all just kept saying 'feed on demand' but my family saw I couldn't cope and advised me to stretch out length of time between feeds. When my DD cried, my dad, or friend, or mum, would take her for a walk, or cuddle her, and often she could be totally distracted for up to another hour. This really made me think well, she couldn't have been that starving then!!! At that weight my DD went longer. It does depend on your baby though... You know him best.
For me, the stretching it out helped ME know she could go longer in the day, but the nights didn't improve much til she was in her own cot in her own room at 9 weeks. She is, and always has been a light sleeper, and I think me right by her, smelling the milk just kept her getting up for it. Having NEVER done more than 3 hours one night, at 9 weeks I put her in her cot (in desperation, I was so exhausted, people kept telling me to try it) and she slept 8 hours straight. 8 HOURS!!!! I checked she was still alive 4 times, and felt like my boobs were going to explode!!! She continued to improve from there.
I never had any joy with getting her to go back on. If I gave her both boobs to try and fill her up more she just puked. I tried lots of things, but not in my room (which I was most reluctant to try, both becuase of cot death fears, and the thought of traipsing back and forth all night to feed her) was the only thing that worked for me.
Good luck!!