One interesting interview question I hear is "How much (in percentage) you know about SAS?"
An interviewee who recently graduated with a master degree answered 90%. He didn't get the offer even he was fully qualified.
I guess once you have a fair estimation of the percentage of your knowledge about SAS, you will know the real meaning of "如何成为一个优秀的SAS程序员?"
And the best answer I ever hear for that question was "I am only good at the modules I use mostly".
It was the best of times, it was the worst of times.