A protective rule can become dangerous when following it is treated as a substitute for noticing conditions.

A rule that replaces observation becomes dangerous. Procedures are built for typical conditions, and following them while the conditions have changed is a way of being correct and wrong at once. The protective value of a rule depends on someone still watching the actual situation.

So when you follow a procedure, keep one eye on whether the assumptions behind it still hold. And where you set rules for others, say explicitly what they are for, since a rule without its reason cannot be applied intelligently when something unusual happens. Compliance and attention are meant to work together, and it is easy to let one substitute for the other.