common wisdom has it that the average programmer (what am I talking about, all programmers live in Lake Wobegon and are above average) spend more than 50% of his time debugging.

Thus, if you by spending 10% more time on coding to make it debuggable and thus save 20% debugging time you have saved in total time.

This fact is so often overlooked just "coding away" (my code will not have bugs, so why worry) and, I believe, is one of the most productivity killing things.

Erik