I tweeted on this a couple of weeks (months?) ago, but it's important enough a concept that I think it bears repeating because it applies to a lot of work that engineers (and, really, anyone) does.
For the less historically-inclined, the Maginot Line was a series of defensive fortifications between France and Germany built between the World Wars. France, tired of Germans tromping through their country every couple of decades, elected to try keeping them out by putting fortifications, guns, traps, and big, strongly worded signs in several languages all along the border with Germany.
And it worked- the Germans were utterly and completely repelled by the Maginot Line's defenses. Of course, they went AROUND them and attacked from the north, but by God, they didn't cross the Maginot Line!
In the engineering world, there can be a tendency to do the same thing. If one manufacturer's product has a defective lot, design them out! A particular technology (e.g, tantalum capacitors) fails you, don't use it again!
It seems like a simple fix, but I'm here to tell you: at best it is only breeding false confidence. At worst, it can actually CREATE a problem, because once a company has suffered through a problem (material contamination, process failure, what have you) that company is LESS likely to have that problem again than another company that hasn't yet made the same mistakes.
The lesson here is simple- learn from past mistakes and problems, but recognize when you're going too far. Ask yourself: am I spending too much time and effort on solving the problems of the last war? Because, I promise you, right now, someone somewhere out there is making something RIGHT NOW that is going to blow up in your product and give you a three-month headache.