This is Camino #5 for me and I know how far I want to walk each day. Booking ahead allows me to look at all of my choices and pick out the ones that suit me the best. Do they have a communal dinner, do they have single beds or beds with pods/curtains, does it have a good feeling about it (did I stay there the last time and enjoy it or not) Walking with a friend this time, so the occasional dbl room ended up being cheaper than 2 single beds, so reserving those made sense too.
Am trying to stay in some different towns, some days not walking as far so that sightseeing can be done.
I booked ahead last spring and had a # of people copy my list. It was nice to walk with zero stress. As a slow walker, it is great to be able to take my time.
After arrival, people were huddled around tables trying to figure out where to go the next night. Seemed they spent hours doing this, the same hours I spent before leaving, except I did my research at home on my PC, with a cup of tea and in my nightgown. This way I got to enjoy my afternoons and evenings while on the Camino.
Most of my bookings are done by email, but have a few in the larger cities done with booking dot com. Same as last year. Had 2 colds last year, so simply moved ahead by bus or taxi rather than walk that day.
Every one has their own comfort level and this is mine.