"There is never time to do it right, but always time to do it over"
I was passed this quote yesterday by a friend, and I see all my software engineer friends shouting "Aye!" :-)
I looked back and realized that most of the time it happens because someone wanted to "make contribution" which was not only unnecessary but also detrimental. Something on the line of "...had to pitch in/stand up and ensure that We ('I') delivered the stuff on time as promised".