Just to add some personal experiences to this conversation, to reduce the amount of confusion, getting a stamp every day does prove you are on the Camino, but it's not the end of the world nor will you be turned away from an albergue if you are missing days worth of stamps on your credencial.
Case in point, there were many occasions where I would enter an albergue and there would be no host, not even a stamper to stamp my own credential to prove I was there. I was not expecting this and I was a little saddened those days that I did not have a stamp, because I never bothered to get a stamp at the cafés or the grocery stores that I stopped in on the way to these unmanned albergues. Nevertheless, the following day's albergue hosts never questioned I was doing the Camino because I was missing the previous day's stamp.
An unique example I have is there was one pilgrim I was walking with on the Frances where she was called back to work in Switzerland. She was no doubt saddened by this, but we all understood. We were in Burgos at the time, and she took a train down to Madrid to catch a flight. About a week later, she met us in Leon because time did not allow her to restart in Burgos. I slightly wondered what the hospitalero would say seeing the week long gap in her credencial, but he just looked at it, stamped it, and assigned her a bed. So if you are missing multiple days worth of stamps on your credencial before the 100 km mark, it's not the end of the world...Finisterre is the end of the world. An inside Camino joke
To add one final experience to the story, my girlfriend at the time was walking with me on the same Camino mentioned above, but she decided to stay a few days at a town several days walk before Burgos, because we met a German pilgrim that injured her leg and my girlfriend wanted to keep her company till our new friend could be able to walk properly. They had to catch a bus to meet me in Burgos, but the albergue in Burgos took them both in without any question.
The one snag they had was, they wanted to view the Burgos Cathedral and get the Pilgrim's discount by showing their credencials. The cashier would not give them the discount, because she did not believe that they both walked 70+ km's that day to get to Burgos. Obviously they didn't, and I was not there to explain this in Spanish (Castellano) to the cashier that could not speak English nor German. Fortunately my girlfriend knew enough Spanish to explain that one of them was hurt, so they had to stop a few days to recover and then take a bus to catch up with me. After hearing their explanation, the cashier thought about it for a moment, spoke to another cashier, and then proceeded to give them both the pilgrim entrance fee discount to the cathedral.