Eli Bendersky's website There is a similar rule, s/synthesizer/compiler/ in the programming world, but there I'm too experienced to have issues with warnings. I simply let no warnings pop up - ever. From the start of the coding, I fix every warning and keep the compilation clean.
But in the hardware world I'm still not too knowledgeable, and from time to time the synthesizer surprises me. For example, half the day was spent today trying to find a bug. We couldn't even approach because some "weird magic" was happening. The "weird magic" came out to be a "clever" optimization by the synthesizer, that cut off a whole flip-flop... It warned us about it though, but I didn't look at the warnings :-( A lot of time could have been saved...
That's the morale for today