Related:

• When you heat with wood, you get warm twice: the first time when you chop it, and then again when you stack it.
• Hear twice before you speak once.
• Measure twice, cut once.
• Once bitten, twice shy
• Measure twice because you can only cut once.
• Once a philosopher, twice a pervert. -- Voltaire
• Try a thing you haven't done three times. Once, to get over the fear of doing it.
  Twice, to learn how to do it. And a third time, to figure out whether you like it or not....
• I had amnesia once or twice. -- Steven Wrigh
• Once is an accident, twice is coincidence, thrice is enemy action.