Mark it, do not delete it
An item on a shopping list has more than two states. You can buy it, but the shop can also be out of it, or you can decide at the shelf that you do not need it after all. Those are three different outcomes, and it pays to tell them apart.
The three marks
- Bought. It is in the trolley, and it leaves the active list.
- Not found. You looked, and the shelf was empty. The item is still open and still has to be bought.
- Not needed. You decided to skip it this time. Not a failure, just not needed right now.
Why it matters
Because at the end of the trip the list should say what actually happened. Delete everything and the next trip starts from zero, with you trying to remember what was missing. Mark things instead and you can see at a glance what is done and what is still open.
It also puts an end to the classic muddle on a shared list: two people in the shop, one cannot find something, and the other has no idea whether to keep looking.
In practice
Mark as you go, not at the end. Next time, the list already knows what was out of stock, and that is usually the thing to look for first, or to buy somewhere else.
Common questions
Why not just delete an item the shop did not have?
Because deleting it throws away the information. An item the shop did not have is not finished with. It is a task for the next trip.
Do the other people on the list see the marks?
Yes. The mark shows up for everyone, so nobody buys the same thing twice.
