You should certainly be flexible around it, visit them every now and then to update. Also, we should enforce them once they are set.
Rules should help you along, perhaps set a framework for your thinking. But they never should limit you in achieving your goal. When establishing a rule you should also specify what you want to achieve by it, how you'll measure its effects and under which conditions it should be removed.
Rigid rule enforcement has a strong danger of shifting the priorities of the developers to the detriment of your business.