Over the years I had plenty of SEO projects from small businesses to enterprise (in collaboration with other SEOs) and from publishing websites to ecommerce websites. As in life, some were successful and some failed.
Due to a certain context, I asked myself what were the reasons that make a project a failure and why other projects keep growing in time, no matter what animals Google is unleashing from the cage.
So far, here are the main reasons that I managed to find: