I have seen programmers that are more than ten times faster than some slow programmers. There are debugging tasks where some people struggle for days, while others would find it in one hour.
You don't win a race by "driving fast", you win a race by never driving slowly. It doesn't matter how fast your car is if you spend 30% of your time stacked up at intersections.
Similarly, programmers spent a lot of time dealing with various barriers to productivity. (For instance, bugs you can't fix) If you want to increase your productivity, you need to attack these barriers by every means necessary.
Of course, there's some real variation in the averages that people will settle down to over the course of hundreds of debugging tasks, but an individual's productivity on debugging tasks varies so much that I'd be hard pressed to say much at all about the individuals until I'd seen them do at least a few trials.
It may be the case that the differences in the average times people take do end up being on the order of 10x or more, but it would take a lot of observation to say that for sure (exactly how much depends on what sort of distributions we see when we measure this stuff).
Interestingly there are articles out there which suggest that one distribution (of competence, rather than productivity, but intuitively you'd expect the two to be related) is actually bimodal rather than normal, "the camel has two humps":
http://www.codinghorror.com/blog/2006/07/separating-programm...