Media reports have drawn attention to the fact that the new archabbot of St. Peter's in Salzburg, Jacob Auer, is only 33 years old. The first thing to recall is, of course, the biblical dimension of that number and its significance in the life and mission of Jesus Christ. And then there was Bernard of Clairvaux, who was made abbot of Clairvaux in his mid-twenties.
Spiritual and hagiographical meditations aside, it turns out that 33 is not even that young in terms of St. Peter's very own history. St. Peter's archivist Gerald Hirtner quickly calculated that Jakob Auer ranks fourth (!) in terms of young abbots. In other words, he isn't even that young. There were significant and hugely successful abbots elected to lead St. Peter's at a younger age, namely Amand Pachler and the supremely significant Placidus Mayrhauser.
These are only some points of comparison from the Early Modern period, for which precise biographical information is available. With an abbey as significant as St. Peter's, whose history reaches back into the seventh century, there were certainly dozens of medieval abbots elected while in their early thirties. 
Postscript, 5 March 2025: Blogger Georg Schrott picked up the ball on this topic and played it back regarding abbeys in the Upper Palatinate in Bavaria. See this report on young abbots there.

Coordinator Tyler Sergent has sent out the information relevant for Cistercian researchers planning to attend Kalamazoo this May. The 2025 Cistercian & Monastic Studies Conference is part of the 60th International Congress on Medieval Studies, held 8-10 May at Western Michigan University in Kalamazoo. It is a highlight of the year in medieval research; indeed the huge conference started out as a rather small annual assembly of .... Cistercian Studies people! Now, thousands of experts and beginning scholars descend upon the sleepy midwestern campus and exchange ideas and build cameraderie. 
The full Congress program is available online here.
Two new developments: there is no longer the daily mass said by monks in a seminar room. Used to be, participants wanted mass daily. I do think there are other masses being said daily in classrooms, but officially there is only the one at 5:15PM on Saturday in Kanley Chapel.
Finally, Sergent writes that the traditional sit-down Cistercian dinner is no longer on the program. "University facilities are not really able to accommodate this kind of event on campus anymore," he explains. There will, however, be a cocktail party with ample time to sit, relax, and visit together. The sit-down dinner used to end with a wondeful, if eccentric, moment when everyone rose from their seats and joined in singing the Salve Regina according to the Cistercian setting. It was – in its own way – a delight! But time goes on, and things change. 

This photo from 1899 shows Cistercian priests from Lilienfeld Abbey at the opening ceremonies for municipal water works in their village. Notice that the laymen at center-left have very high top hats (also the first layman on the right). Most of the Cistercians are wearing hats that are not quite as high. Proper top hats don't seem to be standard for the clerics. Many of the monks are wearing medals on their chests, signs of civic or ecclesial awards and honors. 

It is carnival time, and not a year goes by without someone dressing as a monk or nun or bishop on Mardi Gras. The result is usually not particularly edifying. When kids do it, however, the result is endearing and often reflects more respect for the religious state. Above, we have a Trinitarian missionary on the left and a lovely "Little Thérèse" of Lisieux on the right, even carrying her flowers. Her rosary almost reaches to the ground!
Such juvenile practices are not to be underestimated in their cultural influence. Many saints "played" saying mass as children (Peter Canisius), and missionary magazines for kids would often show children in the religious roles that they aspired to. Robert A. Orsi published about this in 2004: "Children [in the USA] were encouraged to play mass at home using (if they could afford it) make-believe mass kits sold by Catholic retailers or else household objects (if they could not.) Candy Necco wafers were popular Communion hosts among children all over the country." (94)