[lusr]

That's a great way to iteratively develop a new design (which, BTW, is quite a nice improvement) for an existing product, but what if you didn't have the existing product? How long did it take to build the all the dependencies of the photo viewer?

While engineering the front-end can be done on a 2-3 day turn-around, I'm fairly certain that the engineering problems of storing and retrieving the petabytes of photos that Facebook users upload took far more than 2-3 days. If it used existing infrastructure then you need to count that engineering time in too.

I'm currently 2 months into developing the core technology for my project, working 1-3 hours in the evening after a 10 hour day at my client. Much of this work is with new technologies and mathematics/algorithms I'm unfamiliar with. In this situation, being unable to iterate on a front-end UI design in 2-3 days has nothing to do with skill.