A good & experienced UI design firm would have a process in place to apply the best learnings from one field to another. A UI consultant works on multiple projects during his career which could be as diverse as a UI for a CRM system to a telecom services management console to a social networking app. With time they become good a recognizing patterns across products. Take for example user management. By now I think we have probably seen all the requirements there could be for managing users & permission - probably the most common functionality in any collaborative product. We can just look at requirements and tell a client what strategy to adopt and deliver a solution effortlessly which would otherwise take years to evolve.
It is this mesh of knowledge you pay a premium for. As consultants we are able to evolve solutions which would work fairly quickly based on our past experience.
