What are your thoughts on free feeding pups?

Hate to bug you, but I keep hearing conflicting information on free feeding our pup. Have a 7 month old Pit and he's on Wysong - Growth, the bag says to free feed all puppies, the vet says no. The bag states for his size 50 lbs he should be eating only 2 1/2 cups PER DAY, (for older/nursing/pregnant dogs) but that puppies should free feed. Problem is that this guy LOVES this food and I am putting down 6 cups a day, (according to the bag an 80 lb dog only gets 5 cups per day), 2 cups 3 times a day for the last week, thinking he'll fill up sooner or later, but he eats all of it in one shot. I don't want him fat, yet if he's going through a growth spurt, I don't want to deprive him of the food he might need at that time to grow. What are your thoughts on free feeding. If you are for it then for how long/what age do you stop free feeding, or should we just feed him the recommended amount for his weight. We had a Rott that just died at age 9, she was overweight and had a heart attack. We don't want to repeat this killing the dog with kindness error. He is kept active, plays outside for like 2 hours a day, goes on an hour long walk once to twice a day, someone is always home with him as we work separate shifts. I say this because I know dogs like people will eat when their lonely or just board.

Thank you for your time.

Regards,
Penny