Depends what I'm shooting. If I'm shooting solo girl amateur fun stuff 15 to 20 minutes is fine. If I'm shooting a multi girl set for a magazine it can take over an hour.
Shooting commercial porn is not a race, it's about how much you sell the work for. I have had days I made $20,000 doing two scenes.
And I've had days I made $500.
On film depending on the scene I shoot between 3 and 20 rolls. On digital between 80 and 200 frames, depends again on the scene.