I have played 4 hours worth of strikes, 2 hours of Siva Crisis and 2 hours of Heroic Siva Crisis, and have only picked up a single key. The only benefit for me to do these are to open the chests at the end but with such low drop rates, it isn't really worth the time. Incredibly frustrating. Edit: picked up my first skeleton key since October 19th. It is now November 3rd. So far i think I've picked up a total of maybe 6 keys since roi released. That includes the 3 from the quest line.