I think it's pretty non-debatable that dogs have more fun sniffing around and exploring rather than walking by our side. My opinion is that the more obedient and well mannered a dog is, the more freedom it should have.
I would start with loose leash walking and end at full voice control. The more reliable he becomes with commands and the more well mannered he is in the presence of stimuli, imo the more the dog should be rewarded with free time.
I will say that I always start and end my walk in a heel. Coming out for a walk the dog is already hyper, I don't want him thinking he can run around being a butt head. He has to start out in a nice calm heel before he is released to go sniff and pee on whatever he wants. Some walks/runs I never release him from the heel. It's whenever I feel like. A walk doesn't automatically mean play time.