Digressing slightly, but when I was a child my mother worked in the grocer’s shop below where we lived. She developed many talents, including being able to cut the exact weight of butter and cheese ‘by eye’, using a wire and two wooden clothes pegs.
They used to make up customers’ ‘orders’ on Thursdays and Fridays, depending on when the man of the house got paid, and if a substitution had to be made, they had great knowledge of what would be acceptable to the customer!
‘ Oh no, her husband only eats carrots, so no point in sending turnips’ or
‘ Don’t send chocolate digestives, she says she eats the whole packet at once. Send Jaffa Cakes’
That sort of thing!