If I am not mistaken, the new guidelines indicate that you need a minimum of 10 hours off in between shifts regardless of how long the shift was. I believe that it used to be you needed an equal amount of time off as you just worked but it is now down to 10 hours as a flat rate.
In addition, I believe that you can work no more than 80 hours a week when averaged over either 2 or 4 weeks and you need 1 day off in 7 averaged over 2 or 4 weeks.
In addition, moonlighting at an institution which is affiliated with your hospital counts to total duty hours whereas if you moonlight at an institution not affiliated with yours, it does not count.
As for us, we are scheduled for the number of days in the month minus 10 (Chief residents minus 12). Now, some of the days off are either conference days or it may be that you are scheduled from 10pm-8am on a Monday are "off" on the TUesday and come back on the Wed.