Burden

I wiki think that there were plenty of cases where people would rush software out the door and learn things but never put that learning back into the program, and that by analogy was borrowing money thinking that you never had to pay it back.

Of course, if you do that, you know, say with your credit card, eventually all your income goes to interest and your purchasing power goes to zero.

By the same token, if you develop a program for a long period of time by only adding features and never reorganizing it to reflect your understanding of those features, then eventually that program simply does not contain any understanding and all efforts to work on it take longer and longer. In other words, the interest is total -- you'll make zero progress.

⇒ Agility