Consistency will make your design better, easier to use, and practically invisible. It gives the user plenty of room to experience the design in the way you intend.
Designing for consistency is a no-brainer in some cases and a little trickier to understand in others. Quite simply, consistency is the thread that ties together elements in a single design. It also ties together designs across a single campaign or brand, creating a product that is distinguishable, usable and effective. Take special note of all the examples below, each brand is a leader when it comes to consistent and usable design.