SEO is a marathon, not a sprint. It takes time to see results no matter what industry you are in. If the industry is extremely competitive, it takes even more time. There are various ways to measure the success of an SEO campaign over time, but many website owners make the mistake of focusing on the wrong things which can lead to bad decisions and a campaign that suffers due to those bad decisions. The key is to not lose sight of the bigger picture as an SEO campaign progresses, however slowly that may be.