What @Resolve10 said.
I would add that this is always about a balance between intensity, volume and frequency and this balance is determined by your goals.
By definition, the lower the intensity, the more volume you are capable of. For instance, you could probably go out for a walk for an hour a day every day of the week and it would be fine. You would adapt to that frequency, volume and intensity perfectly well.
But if you strapped 150 pounds on your back and walked for an hour - even if you COULD do this for a full hour, maybe you could come back the second day and do it again, but you wouldn't be adapting - you'd be slower the second day, and the third, etc. until one day you wouldn't even be able to pick up the weight. I would guess most people wouldn't be able to do it for that first hour though (you can work hard, or you can work long, but not both) and the second day would be out of the question altogether.
In this same light, if you're going to have high volume AND high frequency - you'd better be closer to your walking intensity. If you're going to go lower volume and you want results, you'd better be closer to your carrying 150 pounds intensity.
Which is better? What is your goal? If you want to be able to walk long distances under a light load for a long period of time, practice walking. If you want to be able to carry as much weight as possible for a short distance, walk with the 150 pounds. In between, all kinds of people will get all kinds of responses. You can build muscle with higher volume and mid-level intensity, or lower volume and higher intensity and everything in between.