What makes a movie long?

Continuing what’s become something of a yearly tradition, films of considerable length have colonized American movie screens this Oscar season, from Hollywood releases like “The Hobbit: The Desolation of Smaug” (2 hours 41 minutes) and “The Wolf of Wall Street” to art house fare like “Blue Is the Warmest Color” (both 2 hours 59 minutes long).

In recent years, high-grossing Hollywood movies have swollen in size to accommodate, and justify, costly special effects. (Business Insider found that the 10 top-grossing movies of 2012 were 20 minutes longer than those from 1992.) But end-of-year, awards-ready films have long gone long. Beginning with silent epics like “Birth of a Nation” (1915) and “Intolerance” the following year, serious-minded filmmakers have captivated (and held captive) audiences for two and half to three hours and beyond.

But just because we’re accustomed to prestige pictures running long doesn’t mean they can’t still be enervating. From the tenor of some recent reviews, you’d think the editor Thelma Schoonmaker forgot to cut “The Wolf of Wall Street.” David Denby’s pan in The New Yorker thrice mentions its three-hour duration, while Michael Phillips of The Chicago Tribune describes a scene that “goes on two minutes too long,” before lamenting that “those minutes add up.” But Ms. Schoonmaker said that was precisely the director Martin Scorsese’s design. “A film like ‘Wolf’ is intended to be sprawling,” she said. “Marty wanted things to go just a little too far in the scenes sometimes, to test the patience of the audience just a bit. Because that’s what the whole movie is about.”

Much as composing a long novel presents different challenges than a short story does, there’s an art to editing longer films. An extended running time allows for more ground to be covered, albeit ground over which pace and rhythm, not to mention the audience’s attention, can be hard to maintain. Few editors have as much experience with longer-form features than Ms. Schoonmaker, who’s worked on 18 of Mr. Scorsese’s features (as well as videos and TV specials) since “Raging Bull” in 1980 (for which she took home an Academy Award), six of which have had running times exceeding two and half hours.