- Do you know what you want?
- Do you know how you'll get there?
- Painting by numbers
- Making a movie
- A Quest
- A walk in the fog
Painting by numbers is regarded as fairly simple and potentialy you can get away with just plain old common sense.
A walk in the fog is a metaphor for someone who is lost. In this case traditional project management can help you get to your unknown destination quicker, but you might not actually want to get there. The agile/iterative approach may be a better bet in these cases, as you shrink the steps and thus the risk of heading in the wrong direction.
Which quadrant does your project fall into? Where do you want to be?
What do you need to get there?