For my first
Camino Frances this year (late April till just now, including resting in Finisterre and Muxia), I used a company in Santiago to make my reservations. I was unsure enough of my Spanish language ability, of how many people would be coming post-Covid and of how much the Holy Year would affect numbers, that it was reassuring to know I had reservations. I also wanted individual rooms because of Covid.
The person in Santiago who owns the company WhatsApp-ed me every day to be check in, be sure I was okay, etc. He was available 24-hours a day if I needed help. This was also reassuring, as an older woman walking alone. He met me at the train station in Santiago to say goodbye. He walks the Camino himself, and takes tours as well, so he knows the accommodations.
So this time, it worked out well for me. I had no physical issues that required rest, and had already adjusted walking distances (not over 25 km).
But you do miss the spontaneity of being able to adjust your schedule--to walk a longer distance when you want to keep up with friends, to walk shorter when it's hot, etc. (I must say, though, that even though I lost some of my Camino family along the way due to schedules, I also had the opportunity to make more than one Camino family, and am grateful for all of the relationships!)
For a first time, I was glad I did it the way I did. But if I'm lucky enough to do it again, I will make reservations myself only couple days in advance.