I live my coding life by this philosophy: The best code is the stuff that looks like any novice could have written it, but only an expert knows how hard that is to do.
(bonus: write your code like the next person to work on it is a psychopath and they know where you live)
Engineers sometimes want to overengineer things that would work just fine in that situation. I remember an old link about someone studying the source code of a game (Doom maybe) expecting to find beautiful solutions for every minor problem when in fact he was surprised by how most of it was straightforward.
Check what needs to scale/be resilient before reinforcing the code there (and of course, if the solution is already frail at the moment it probably needs to be fixed sooner rather than later)