I also asked two different vets on the matter. I of course got two different answers which kind of annoyed me, but it is what it is.
One said that repetitive is better for building up the muscles and believes that walks are better.
The other said that repetitive is bad as it wears down on the joints and free play is better as the ground is softer and the dog will vary it's gait and quite when it is tired. This is what I have personally heard the most.