I recommend carrying just 2 t-shirts. You wear one and carry one. When you shower in the afternoon, you put your clean shirt on and immediately wash the one you just wore. You do this every day of the Camino.
Deciding what sort of shirt to take on the Camino can be tough. Mainly because when you go to one of those outdoor stores, there are so many types. The most important thing about the shirt you carry is that it’s comfortable. The next consideration should be how quickly is it going to dry.
First of all, wool shirts are comfortable, warm and layer really well. They also dry quicker than ordinary t-shirts you might buy at standard clothes store. In other words, they are perfect for the Camino de Santiago. The problem is that they are expensive as you can see on Amazon. Expensive but good. If you can afford them, buy a couple!
If not, you’re really looking at a standard t-shirt. The problem with standard t-shirts is that they don’t dry that quickly. If the weather is good and the albergue you are staying in has decent drying facilities (as most of them do), the t-shirt will dry overnight no problem. It’s just that if you want to wash it and bring it before you go to bed, you may have trouble unless it’s a hot sunny day and the albergue’s clothes line is in the sun (often not).