How does depletion work in Die2Nite?
Solution 1:
Zone depletion is based on set numbers. Each zone when you start a new town has 6 items in it. Each building has 10 items in it. This is not 6 & 10 searches, this is 6 & 10 items to be found.
If an area is replenished by the search tower, it will gain between 1 and 10 items. If a building is replenished, it will always be back to the full 10 items. Buildings and zones are treated seperately, so the zone may not replenish but the building will, and vice versa.
Each zone has a cap on the number of items it can hold. This cap is 20 for each zone. So the way this works for example, if a square has never been searched (6 items) and is then affacted by the search tower also (1-10 items) that zone would then have anywhere between 7 and 16 items in it. AT that point it would be very important to make sure the zone is depleted before its effected by the search tower again. If it had not been searched and was replenished once again, it would then contain between 8 and 20 items. Potentially you would be losing 6 items becuase of the cap. You cant actually tell if a zone that has not been depleted has been effected by the search tower or not as it is already showing as undepleted, the only way to find out is to deplete it and see how many items come out.
For buildings, I unfortunately cannot confirm if there is a cap of 10 or 20. To be safe you are best to always deplete a building before the zone is replenished again.
Solution 2:
I believe that mordi's answer is correct, a zone has a set number of items in it, then it will be depleted. So a fresh zone that has never been visited is a better place to auto-search than one that has had a lot of people in it, even if neither of them is depleted yet.
The search tower adds some items to depleted zones, making them undepleted again. However, the number of items added seems to be significantly smaller than what a fresh zone has.
Building depletion is separate from zone depletion. You can still find items in a building if the containing zone is depleted. Each person can only search a building once per day. You will know when the building is depleted because you will get a message when you search it that says you are sure there is nothing else left.
The search tower undepletes buildings separately from the zone containing it, so you should always try to search buildings even if they were depleted previously and the surrounding zone is depleted.
As a bonus tip, our town has started using the "Uncleared zone" marker to indicate zones that are not depleted. This marker is useless normally (since you can see that there is an unidentified building anyways), but it helps to distinguish a zone that someone has verified is not depleted, versus a zone with no marker which might be depleted and someone forgot to mark it as such. Of course you still have to rely on people changing the uncleared marker when they deplete the zone.
Solution 3:
A zone contains 4-24 items, before it gets depleted.