It's possible, but I'd be pretty shocked. I've been doing mindfulness meditation for a few months and I feel fairly confident in saying that the belief that "the operative part of meditation is sustained concentration" is a misconception. When you meditate you allow yourself to become aware of your body sensations but you don't force yourself to concentrate on them, and I don't think that most meditators explicitly try to maintain concentration when they sit. (That said, after ten or fifteen minutes of meditation concentration often becomes natural.)

It certainly has seemed to me that the important part of meditation is the relaxation that it lets you achieve. I think it's literally impossible for me (at least) to get as relaxed as I am after a typical hour of meditation by any nonmeditative means. (If you interpret "relaxation" as having low blood levels of e.g. cortisol this is actually measurable.) And I know that I have days when I don't sufficiently relax myself when I sit, and I usually don't see the same benefits that I do from "good" sits. 'Course, a lot of this could be confirmation bias.

Also, anecdotally, I maintain substantial concentration for 30+ minutes a day because that's what studying is, and the short- and long-term effects of that concentration don't seem to be anything like the effects of meditation.