Let us see five proverbs which fit perfectly to the rapid development scenario.

An ounce of protection is worth a pound of cure.

A little precaution before a crisis hits is better than lot of firefighting afterwards.
Many times, developers neglect risk management. Risk management, identification and prevention are more critical than we think. Unidentified risks cause a lot of trouble in the later stages of software development. This is why, preventing such risks is wiser than to fix them after they get worsened. Identifying risks and taking precautions against them, that is protecting the project against the risk is a key to rapid development.

A stich in time saves nine

Correction at early stages saves work later.
In a software development lifecycle, doing right things at the right time is very important. If work is delayed in the earlier stages, it can causes much trouble afterward. Example a flaw in the design time is not fixed is bound to cause a disaster. And one flaw in the implementation time if not fixed will take almost triple the time to fix at the debugging phase.

Cross the stream where it is shallowest.

Don't complicate things unnecessarily.
Many developers believe that the more complicated things will be made, the better the project will execute. But that's not the case. In reality complicated practices, stringent methodologies actually lengthen the process rather than making it faster. This is why many times the simple is the best. Complex design patters, complex code leads only to increasing the clutter of the program. Yes, this doesnt mean that one must nor use complex patterns or code. This means that one must always strive for a simpler solution to the problem.

Watch the doughnut, and not the hole.

Focus on what you have rather than at what you don't.
In a software development lifecycle, one cannot get all the aspects perfect. In that case, you need to maximize what you have over what you don't. For example you might not have trained personnel, or say might not have enough time. But in such cases, you must focus on what you have and try to give the best possible. Focus on your strengths and try to win the match.

Too many cooks spoil the broth.

If too many people are involved in a task or activity, it will not be done well.
This is often the case with software development scenarios. Too many people who are experienced and have their own different viewpoints. While difference in perspectives always leads to better ideas, there must be only one decision maker whome everyone must follow. Disagree but commit must be the case with those who are the subordinates. If too many people are decision makers, then it will lead to chaos.