The real lesson here, which is timeless, is that you're safer if you understand why your favorite rules of thumb got to be that way. Did you learn the hard way,

The real lesson here, which is timeless, is that you're safer if you understand why your favorite rules of thumb got to be that way. Did you learn the hard way, from a particular set of circumstances? Do those still apply? Is it a natural consequence of lower level principles? Do you still believe those? Or maybe someone you respect told you to do it, or it just sounded good. Not bad reasons to do things, but knowing that's all you're working from gives you a hint that you should be opening to change your mind.