People improve solutions iteratively. What that means is that when faced with a problem, people come up with one possible approach. To make the approach better, people think about shortcomings the first approach had and then improve on it.

This has a few consequences:

• Unless they explicitly aim to, people don't normally go "backwards": try and start over from a previous point.
• The first solution that's figured out ends up driving the iterative process.
• Working with other people can be difficult, since we're not really used to parallelizing the problem solving process in our own head.

References:

Michael Kronovet