There is a new, statistics packed posting at Popes and Papacy, as of May 2, 2010, pertaining to cardinal creating consistories — looking at trends since 1900.
It has three ‘master’ tables of trends and two smaller ones showing how Mondays, ideally in December or June, used to be the preferred days for such consistories. Fifteen successive cardinal creating consistories, as of 1900, were all held on Mondays. All of the cardinal creating consistories held by Pius X (#258) and Benedict XV (#259) were held on Mondays. Pius XI (#260) also held his first on a Monday. Then five months later, when it came to his second cardinal creating consistory he opted to have it on a Wednesday — in May. His next one, in December of that year was on a Sunday. But after that he too feel into the Monday is the day routine.
Pius XII (#261), John XXIII (#262) and Paul VI (#263) all made sure that their cardinal creating consistories were held on Mondays.
None of John Paul II’s (#265) nine cardinal creating consistories, during which he created a record 231 cardinals, were held on a Monday! But, he liked specific dates — e.g., June 28.
The current pope, who was greatly influenced by his predecessor, appears to also shun Mondays — though we are not sure why these two popes made a point of breaking the Monday’s tradition.
See more of the trends and understand the issues facing Benedict XVI when it comes to creating new cardinals by reading the Popes and Papacy post.