Not if he does the type of job hopping typical in silicon valley. There are plenty of programmers who only stay at a job ~2 years, and never have to maintain a

Not if he does the type of job hopping typical in silicon valley. There are plenty of programmers who only stay at a job ~2 years, and never have to maintain a program over a long period. You could imagine such a person saying 'this worked well at my last job' and just keep introducing that kind of pattern to new companies, eventually with '20 years of experience'.