As a designer, I'll be the first to say it's really easy to get carried away. The designer is always concerned about empowering the end user through design. They end up doing extensive research, wading through absurdly huge amounts of information to distill an end product for the client. Left to their own devices, it's all too easy for a designer to turn this into an endless loop of design, revision, prototyping, more revision, etc
This is where the concept I like to call "Shoot the Designer" comes into play. It's critical to figure out what is good enough for the end user, as perfection is simply not practical in every project.
Experience is a key factor in deciding when it's time for a design to move to the end phase. This is where a good product manager or sales VP come into play, as their outside view is sometimes the key element to breaking a design logjam. At i4c, we have extensive experience working with executives and high-powered salesmen and have refined the art of knowing when to let a design go to production to a master level.