Probably not. I would expect housekeeping to be checking the room (even if you put out the DND sign) and report the room vacant after their second attempt to clean the room. Normally the front desk will check you out and close the folio at that time. Would your company be ok paying for two weeks you're not there? If you really think you can get out of there earlier, I'd suggest booking multiple reservations covering the three weeks and then you can cancel the ones you don't need.