All general rules like this are terrible if you apply then blindly, but can still be useful if you apply them loosely. In your example, I would take simple to

All general rules like this are terrible if you apply then blindly, but can still be useful if you apply them loosely. In your example, I would take simple to mean "only use UTC". As soon as you need timezones I would say you've moved into correctness territory and need to do them all properly (you would use a good library, of course).