Dd eats with us and will sit and eat for around five to ten minutes before getting up to potter around. She generally comes back and eats more sitting on my lap. Dinner is over when dh and I finish because then we clean up, so all up dinner can be half an hour to forty mins long depending on how much dh and I chat etc. We always tell dd it's her last chance to eat because it's clean up time and then she'll often have a few more mouthfuls. Breakfast can go on and on bevause dh gets up after me so she has two rounds. Lunch we eat together and is about fifteen minutes or so?

I would encourage the big table too and try and involve him in the ritual of a meal....so set up serve and then pack up so he knows it's not just about snacking.

Maybe he has a small tummy and needs lots of little bits?

Good luck. You're doing a great job!