Using Agile development methodologies, we promote the implementation of complex systems in small development cycles (typically 2-4 weeks), and delivering, at the end of each cycle, usable working software, thus allowing the users to immediately evaluate the delivered functionality and adapting their requirements to their real needs, instead of sticking to the requirements frozen in the beginning of the project.
At the end, the final product meets the expectations of users, since they actively monitored the implementation, reducing the risks of failure of the projects.