Five times, once per-week since I've had a character capable of doing so and my shoddy attempts to find a worthy team (now I'm glad to have many! ^-^) Just today I managed to pull Vex and Timebreaker from Hard Atheon, given I've also found The Last Word from the Nightfall and one Bad Seed Down from an engram (still prefer my Super Pox VLO) I'd say it's a wonderful day.