Here's Smith's beef:
Another lamentable creeping usage is not only pretentious, but it distorts and narrows what artists do. I refer to ... the word practice, as in "Duchamp's practice," "Picasso's studio practice" and worst of all, especially from the mouths of graduate students, "my practice."
She is attempting to take a perfectly serviceable art word out of commission here. It's like saying we shouldn't use red to describe that warm color next to orange on the spectrum. Or the Castro-esque dictator in Woody Allen's Bananas declaring the official language of San Marcos to be Swedish.
Let's take her examples. A historian might use "Duchamp's practice" to distinguish something the artist did from something he thought or wrote, e.g.: "It is a matter of scholarly debate whether chess merely informed Duchamp's theory or could be considered part of his practice." Ditto the Picasso example--you could use "studio practice" innocuously if you wanted to differentiate the artist's studio work from, say, his mural-painting.
As for a grad student saying "My practice"--yes, it sounds pretentious as a description of two years' worth of work and is probably the phrase that set Smith off. But one wonders why a Times critic is hearing that. Could it be because hot grad students are considered the only viable players in the current art market? Maybe that's what she's really mad about. Professionally, she *has* to listen to these people.