Schedule E: "days rented at FMV"
When considering the "days rented at FMV", how does occupancy factor in?
I.e., a vacation property is rented for 30 days, tenant has paid in full the 30 days, but decides to leave/vacate after 20 days (personal choice, no issues or conflicts). No refund for unused rental is given. The property is then vacant and available for rent the remaining 10 days, but the full 30 day rental is still paid. Do the "days rented at FMV" remain at 30 since that is what was rented and collected, or do they change to 20 now that it is unoccupied and available for rent (even though rent has been previously collected)?
TL:DR How to classify usage for a property that is simultaneously available for rent and rented.