Since the sun sets late (after 10pm) and we typically end up inside the albergue by 10pm, evening exposure to mosquitos should be limited.
Also, if wearing a lightweight, long-sleeve backpacking shirt/windjacket and long pants/tights in the cooler morning air when first starting out, we tend to minimize contact. And, those can be used if in areas where there is likely daytime exposure (moist, shady areas, forests, rivers/canals, etc.).
Some mosquito attractants are the scents given off by specific bacteria that grows on the skin and within the clothing. Some people grow those bacteria more than others based on their own body chemistry; I am one of those, and mosquitos find me rather attractive (thankfully, I'm not as highly reactive to their bites as some appear to be here). Therefore, I made sure to shower carefully and used washing machines when possible for more thorough cleaning of my clothes than I could get with a sink and a bar of soap.
Just with clothing selection, timing of walking, and careful hygiene, I never even needed to apply repellent from late May through mid July 2013 on the CF. I'm not sure I'm even going to take any this time around because my pilgrim habits make me less susceptible to bites than in my own backyard in the evenings.