If something doesn't make sense, you're not seeing something.

I came to understand that one only after banging my head against it a dozen times. Usually it's a situation where the code appears to be perfect but won't run so I spend a few hours tweaking the perfect code into other equally valid versions, trying to force it to make sense, until I snap out of this moronic fog and check the config files or the environment or whatever and find that someone turned on something crazy somewhere or XYZ got silently upgraded to the wrong version or whatever.

Seems stupid but once I finally realized that if it looks right but runs wrong, I almost never have to fix it, I just have look elsewhere. The amount of time I've saved lately with this is *slowly* adding up to the amount of time I've wasted in the past fighting against it.