As to well documented flat rates piece work is not cut and dry in repair shops. Who gets the warranty work who gets the customer paid labor. Then who gets the light fast work such as tune ups and who gets stuck with the heavy slow work. Beat the book vs the book beats you. Then who gets the work that can be done faster then the flat rate book time and who gets the work that aways takes longer then what the flat rate book allows. Always mecanics complaining who's getting all the cream work, whole milk work, no fat milk work, powedered milk work and you have to supply your own water. Then the comebacks, where what ever time you spend to fix the problem a second time you don't get paid for the additional time you spend on repairing the problem for the second time.