A customer came in describing a scent her mother had worn for years and had bought in this shop. Her mother had died, the bottle was long finished, and nobody had written the name down.
What she had was a surname and roughly the years. The cards are filed by name, so it took about twenty minutes to find three purchases between 2009 and 2013, all of the same oil.
We still stock it. She smelled it before we said anything, which was the right way round, and it was correct.
We tell this story because it is the whole argument for the card drawer, which costs us a filing cabinet and five seconds per sale. She has bought it twice a year since.