I absolutely won't free feed for a couple of reasons - and they may be largely breed specific for me.
1.) Each dog has a different metabolism, food need, ect... and by measuring and only leaving food down for 30 minutes twice a day I can moniter what each dog is or isn't getting.
2.) I have a couple of picky eaters that would never eat anything if I didn't make sure they knew that the food only sticks around for so long.
3.) I think that by having meal times the dog learns quickly that you are the pack leader and provider.
With a puppy they should be getting 3-4 meals a day at a scheduled time. I feed my puppies (8 weeks and older) 3 times a day at 8 AM, 1 PM, and 6 PM. They get "meal time" and I leave the food down for 30 minutes. If it's not gone, the food still gets picked up. It takes about 2 days for a new puppy to understand they need to eat right away - but they also realize they get plenty of time so they do chew every bite and aren't rushed - they just don't walk away from their dish.