Fixing results at the end of the line, not the decision that caused them, costs again every time and hides which decisions were sound.

The claim

When an outcome comes out wrong, the common repair is a tactic applied at the end that forces the result into shape, rather than a change to the decision that produced it. Both can make the result look right. The end-of-line fix has to be paid for again every time and leaves the cause in place; the design fix is paid once. An organisation that relies on end-of-line fixes also loses the ability to tell from its results which of its decisions were sound, because the fix hides the fault. The case offered is an assembly line where a worker taps every door into fit with a mallet, against a line where the door is designed to fit.