I've been an external and internal auditor for fifteen years and I've never heard of this "golden rule". Sounds like someone wants to go back to "auditing by the pound". When I select a sample I enter the sample into a spreadsheet, with various details (customer name, account/loan number, transaction amount, date, etc.); enough to allow a second person to pull the same source documentation I did and come to the same conclusions. I can't imagine any accounting systems these days where prior records aren't archived and easily obtainable (subject to record retention rules). I will keep copies of exceptions, as others mentioned, to enable the reviewer of my workpapers to see the exception noted and support the conclusion that was made.
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"The words you say never seem to live up to the ones inside your head." Chris Cornell (Soundgarden)