I, too simply follow the arrows. However, when the weather deteriorates seriously, or my hips knees or ankles resonate in a chorus of "nada mas," it is nice to be able to know exactly where I am in relation to where I would like to be. It helps me plan forward.
Occasionally, I have to resort to taking a taxi or bus to finish the daily planned distance if my aging joints are simply too painful, even with pain relievers, anti-inflammatory medication and elastic braces. When I am presented with a challenge, I simply adapt and overcome.
I do not follow the GPS track. But I DO have it running in my pocket or belly bag. This way, when and if I need to refer to it, it is ready to tell me what I want to know.
Before I depart, I develop a MS Word table of my "walking plan." It has columns for date, day, destination, Km, elapsed Km, and Km remaining to Santiago. It also has columns for where I have reserved lodging for the night.
The table is orientated in landscape mode. I carry it in my cargo pocket, in the waterproof pouch with my credencial and national passport. I also leave a copy with my family so they know where I was expected to lay my head each night.
Where I do not have reservations already made, the lodging column also contains the phone numbers of several likely places TBD to stay that did not have online reservation capability. This way, I can ask an innkeeper to call the night before, or two nights out, to make a phone reservation on my behalf. My Spanish is improving, but is not yet fully conversational. In my experience, this always works.
Hope this helps.