Benedict himself was elected on the fourth round of voting in 2005, a day after the conclave began — one of the fastest papal elections in recent times. His predecessor, John Paul II, was chosen following eight ballots over three days in 1978.
In the past 100 years, no conclave has lasted longer than five days.
On Tuesday, the conclave will begin with a morning Mass in St. Peter's Basilica, followed by a procession into the Sistine Chapel and the first round of secret balloting in the afternoon.
If black smoke is sent snaking out of the chapel chimney to indicate there is no victor, the cardinals will retire for the day. They return Wednesday for two rounds of balloting in the morning and two rounds in the afternoon, a process repeated each day, with occasional breaks for reflection, until a pope emerges.
U.S. Cardinal Timothy Dolan, considered a papal contender, said in a blog post Friday that this week's preliminary discussions covered preaching and teaching the Catholic faith, tending to Catholic schools and hospitals, protecting families and the unborn, supporting priests "and getting more of them!"
"Those are the 'big issues,'" he wrote. "You may find that hard to believe, since the 'word on the street' is that all we talk about is corruption in the Vatican, sexual abuse, money. Do these topics come up? Yes! Do they dominate? No!"
The Americans had pressed this week for time to get to the bottom of the dysfunction and corruption in the Holy See's governance that were exposed by the leak of papal documents last year. Vatican-based cardinals had been angling for a speedy end to the discussions, perhaps to limit the amount of dirty laundry being aired.
But by Thursday afternoon, Cardinal Roger Mahony of Los Angeles tweeted that the discussions were "reaching a conclusion" and that a mood of "excitement" was taking hold.