For Germany, that's only a 2-1/2 month supply.

Maybe but that assumes zero LNG imports and zero gas from Norway, which will not be the case. According to Germany they have enough gas for the winter.

Do you have a recent source for that? The sources that I checked a few days ago all say that there's enough to get through the winter without any bigger changes (except maybe lowering consumption a bit): https://www.tagesschau.de/wirtschaft/unternehmen/gas-speiche...

The reserves are a buffer to allow smooth supplies during the increased winter usage. The reserve sizes were set assuming a continued flow of gas.

So allowing the reserves to fill to 90% does not lose Putin the game, it gives him increased time to keep the citizens in suspense, thus creating doubt and confusion.

And it gives him money. War is expensive.