This is exactly how I walk my dogs, except I use a 30' long line. I have a command for loose leash walking, one for focused heel, one for come this way but you don't have to be right next to me, and one for go wherever you wish.
I use the free command as a reward for good behavior for a portion of the walk. I encourage them to sniff and check stuff out. I even point out things for them to check out. Then we go back to loose leash or focused heel for a bit. Throw in some OB, random nosework or hide and seek in the woods, and you have yourself a pretty great walk for you and the dogs.
Thanks...good info, I'll expand on this new liberty the dog has earned.