A one day test walk won't provide an answer to the question: Can I keep up my test walking pace day after day for however many weeks you will be pursuing your Camino?
An example: For many, blisters don't occur until day two or three. During the first day or two, unnoticeable pre-hotspots begin to happen; feet feel sort of like after walking a ways barefoot on warm concrete or asphalt. It is an understated feeling of subtle rawness. When looking at the bottoms and heels of one's feet, they feel a bit tender, but there are no obvious blister formations or hotspots. This is when preventive taping needs to be rigorously done, but frequently, most won't.
During days two and three, the feet, having been subjected to the previous day's insults and now being tasked to continue walking yet another long distance day, begin to develop significant hotspots and blisters. Until one is doing multi-days of long-distance trekking, they will not know if the above will apply to them, or if they will be blister free.
Achilles tendons may respond to the unusual amount of repetitive walking by becoming tender and a bit swollen; sure to become a problem if not dealt with in the early stages of inflammation.
A new pattern of daily long-distance walks will also put unusual strain on the arches and plantar fascia... Being new to long-distance walking over many weeks, untrained feet may go ballistic with all the new stresses and pounding that they must now adapt to.
Shoulders, upper back and neck muscles all become strained from carrying backpacks loaded with pounds/kilograms of weight that they normally don't tote. Although most of the pack's weight is shifted to the hip belt, the shoulder girdle still carries some of the weight and keeps the pack from flopping backwards. Attention must be paid to those areas so that soreness doesn't become inflamation and agony.
The lower back is dealing with about 75 to 80% of the weight of the pack via the hipbelt. Aches and pains may occur that become increasingly aggravating by having to carry one's pack day after day.
Knees, ankles, shinsplints (ugh).....
All of the above, and more, are what a single practice walk over 14 miles will not reveal to you prior to the Camino. That is why you need to focus more on paying attention to what your body NEEDS you to do, mileage wise, and ease into the daily mileage. Let your body harden into its new found physical activity..... allow time for your body to adapt. For those who are not experienced long-distance walkers, thru-hikers, or trekkers, trying to push your body too soon is a recipe for misery.
Let your body be the one dictating your pace. If you follow that advice, you will find that the daily distances you walk on the Camino will increase over the following days and weeks.
Buen Camino, Pilgrim.