2-ply? What are you, rich?
I've been using the same Sears and Roebuck catalogue for the last 6 months
It's getting hard to find a "typical" roll any more. mostly you see jumbo rolls and mega rolls and stuff like that. But I have found that when I have a job I use exactly one roll per month, and when I am off I use exactly two rolls. Now I buy Charmin "mega" rolls a dozen per pack, equivalent to 36 rolls and they last exactly 18 months.
I would say 2 weeks. With a woman in the house it makes a big difference. :)