My contributions/spins on this:

The most general problem cannot be solved. (If you don't limit scope, you will never finish. You won't even finish the design.)

If you want it bad, that's how you're going to get it. (That is, rushing a project means you get crummy results. This may be "Hanka's Law", because I first heard it from Steve Hanka, but it may not be original to him.)