If testing costs more than not testing, then don't test.

The business changes. The technology changes. The team changes. The team members change. The problem isn't change, per se, because change is going to happen; the problem, rather, is the inability to cope with change when it comes.

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, How would I develop if it were my money? I'm amazed how many theoretical arguments evaporate when faced with this question.

Make it work, make it right, make it fast.

How good the design is doesn't matter near as much as whether the design is getting better or worse. If it is getting better, day by day, I can live with it forever. If it is getting worse, I will die.

If testing costs more than not testing, then don't test.

I tell people to start implementing when they are pretty sure there aren't more important stories out there. An iteration's worth of data is worth months of speculation.