Mary, always check with the hospitalero, the person at the bar, and on the church door, as well. Things change and sometimes there is mass when you least expect it, other times it's no longer happening when all your guidebooks say it is. I had it happen both ways.
Mass was a priority for me and between St. Jean and Sarria I was able to attend mass in 24 towns. St. James provides. They almost always include a pilgrim blessing, often unique and very moving.
Also, many little chapels along the trail are open for prayer and reflection. Check the door to see if it opens. Some places that looked abandoned turned out to be open and beautifully cared for inside. Love those surprises!