From my experience they don’t do anything extraordinary. Except that they tend to deliver results 2-10 times faster and produce much cleaner and scalable code.

From my experience they don’t do anything extraordinary. Except that they tend to deliver results 2-10 times faster and produce much cleaner and scalable code. And capable of designing elegant solutions of a more complex problems than their less experienced peers can handle. And they feel/understand the requirements much better and quicker.