Earlier quoted context omitted.
Or maybe if putting a piece of paper on someone's desk for precise restocking is too much of "a pain" to the person who drank the milk, then they should rethink their employment there.
The job of the person drinking the milk presumably has nothing to do with moving cards to people's desks. The job of the office manager is literally to keep the milk stocked. When keeping the milk stocked becomes a sidequest for every other employee (who have other jobs to do), what is the office manager actually doing? Bringing the card to the office manager's desk doesn't actually sound much harder than ordering mo…
Bringing the card takes 5 minutes, 10 if you include time to a joke like "We are drinking too much milk, we should buy a cow next year."
Buying the milk includes going to the shop or calling the correct provider. Not the provider you used until two month ago because they usually deliver the requests too late at 5:05 when everyone is going home. Are you paying with the company card or your card and get reimbursed or they have to send an invoice and get paid later? Does the invoice need a magic tax number? Ensure they security guy and the payments department know about this so there are no surprise. [1] [2] This looks like half on hour at least.
When someone ask me to implement a trivial feature in software, I estimate "4 hours". Open the editor, find the correct file, take a look, make the obvious change, run the automated test, fix the obvious bug, cross the fingers, run the test again, [does it need new tests?,] write a nice commit message, google how "thoughtfully" is spelled, commit the change, close the editor, and it's done. Probably 2 hours, but I prefer to say for 4 hour in case there is a surprise.
[1] How many milks? 1%? 2%? 3%? Which brand? This may be included in the instructions, but in the second week of December you may want to buy less, and if there is a discount you may want more.
[2] Do you piggy back cookies or soap?