A warranty is a company betting on its own work. Do work you’d bet on.

A guarantee is a confession made in advance. A company willing to replace the thing is telling you what it privately believes about how the thing was built, and one that hedges with twelve conditions is telling you that too. The same reading works on people, and it works on your own work once you are brave enough to try it.

Look at something you are about to hand in or hand over and ask whether you would still stand behind it in three months. If not, you usually know which corner is the soft one. Give that corner twenty minutes instead of polishing the part that was already fine.