That might or might not be the same kind of thing that my brain responds to. If it is:

It is easier to keep in mind a consistent Rule than to remember occurrently what justifies it and check for those conditions every time. If there is a really good reason to break a Rule, it will intrude itself upon your notice without explicit checking, so it's safe to just go around following Rules until and unless that happens. Assuming you had a good reason to implement a Rule, it's correspondingly bad to threaten its force (by ignoring it when it's inconvenient, for example - inconvenience-related exceptions could have been built into the original rule if they were really worth the extra checking and if they are genuinely well-defined), and you should be highly suspicious of yourself if you start coming up with great reasons to change your Rules whenever they get inconvenient.