I have 3 children with another on the way. My first born nursed like you are describing. Since she was my first and I was committed to staying home full time, I did not mind at all that she nursed constantly. I swear, my first born could just suckle all day if I let her. My second born was a "down to business nurser." She took what she needed and was done until the next nursing session. With baby #3, I had issues with him from the beginning and our relationship with nursing was cut short when I had to supplement with formula. Every baby is different, as you can see.
You need to make sure that your baby is indeed nursing for at least 10-15 minutes on one or both breasts. Switching breasts is not as important as allowing the baby to nurse as long as possible on one side because it is the rich hindmilk that will give your baby the fat (a.k.a. "weight gain") that is much desired. Any longer than that could just be suckling for comfort but for some babies, this suckling gives them great comfort and do not think the baby is not still getting milk. Even when the baby is suckling, the baby is indeed getting milk from your breast. Is he producing adequate wet diapers and any poopy diapers? The biggest clue is if he is gaining weight. You should be taking him to the ped 2 weeks after his birth for his first official check up and at this time they will weigh him. At 2 weeks post birth, he should have regained his birth weight. All newborns lose some ounces after they are born and this is normal. If he is gaining weight, coming off the breast content (no matter how long he nurses), is producing wet and poopy diapers, I say don't worry at all. Some new moms fear their baby is not getting enough because they can't see how much breast milk the baby has actually taken in.
And whatever you do, always feed your baby on demand! Newborns/infants digest breast milk very quickly and it is NORMAL for an infant to nurse every 2-3 hours. Putting the baby on a "schedule" is not only bad for your milk supply, but it assumes that only you know when your baby is hungry. Let your baby tell you when he is hungry and your breastfeeding relationship will thrive very well.