Whether you want to walk half a day or you just can't take it and want to stop walking, there's always a way to get to your final destination by the end of the day.
You can sleep in, take a taxi to the halfway point, and start walking midday. Or you can stop at any village, bar, and get a taxi where ever you want to go.
Public buses are also available in certain parts.
You need to monitor yourself and be aware of where you are. If you sit down at a cafe and see that the next village is miles away and you don't think you can make it, then call a taxi there.
BTW - there is no Uber or Lyft in northern Spain. I've tried.