"Design adds value faster than it adds costs."
-- Joel Spolsky
This quote from Joel Spolsky (creator of Trello, among other significant accomplishments) is a delightful reminder of what design is, and what it should be.
That is, design should add value faster than it adds costs. While working as a designer, it's very easy to get drawn into creating elaborate designs and perfect prototypes. But the goal should always be to inform the correct solution as quickly as possible, as Spolsky so succintly articulates.