You will be interested in this then :
I was as surprised as you probably will be after reading this. It is officially advised to not keep resin in standard tanks for more than 1 month, and 2 months for LT tanks. This seems like a sentence that has been placed there in order to avoid having to pay for catastrophic tank leaks in the printer.
Needless to say, my several standard tanks do last much more than 1 months and I certainly do not empty them when I do not plan on using one of them for more that that amount of time, it would completely destroy the workflow that makes the Form2 so easy to use.
If there is really a risk of damaging the PDMS or anything else, then what about a tank that is used once or twice a week for very small prints such that the tank lasts more than 2 months ? This use case would be pretty normal.