The Vatican has a suggestion:

Homilies should be no longer than eight minutes — a listener’s average attention span, said the head of the synod office.

Priests and deacons should also avoid reading straight from a text and instead work from notes so that they can have eye contact with the people in the pews, said Archbishop Nikola Eterovic, secretary-general of the Synod of Bishops.

In a new book titled, “The Word of God,” the archbishop highlighted some tips that came out of the 2008 Synod of Bishops on the Bible. The Vatican newspaper, L’Osservatore Romano, reproduced a few passages from the book in its March 10 edition.

The archbishop wrote that it’s not unusual for preachers to recognize that they have less-than-perfect communications skills or that they struggle with preparing homilies. Everyone should spend an appropriate amount of time to craft a well-prepared and relevant sermon for Mass, he said.

He said Pope Benedict XVI starts working on his Sunday homilies on the preceding Monday so that there is plenty of time to reflect on the Scripture readings from which the homily will draw.

Archbishop Eterovic praised an initiative by the archdiocese of Paris, called “Improving Homilies,” that has been offering courses and guidelines for priests and deacons

Among the guidelines’ many helpful suggestions, he said, is that “the homily in general should not go over eight, minutes — the average amount of time for a listener to concentrate.”