[lmm]

"Cannot harm" is a fallacy. Every additional comment adds a maintenance burden.

Sometimes comments are worth the cost, but they should be a fallback to a fallback - ideally, the code should be self-explanatory. If that's not possible, unit tests should explain the usage and functionality - they're better than comments because the build system enforces that they're updated when the code changes. Only if you can't do that either should you resort to a comment.