Graduate students who have been working for about five years, however, have the option of remaining at Harvard to write and teach.

"Usually people just wait to defend [their dissertations] until they have a job, since you're only cutting off work opportunities, the possibility of teaching here," James says.

Institutional affiliation, extra time to publish, and more lines on a teaching resume can make the extra year worthwhile, says Shyon S. Baumann, a sociology student who will graduate in June and does not yet have plans for next year.

Spending an extra year working on a dissertation also reassures job interviewers who fear that candidates will not finish their dissertations by the time the job starts.

"Because you're not really sure when your dissertation is done, there's a subtle distinction between extending the dissertation [based on the job market] and spending more time to improve it," Baumann says. "You may decide you need an extra year in order for it to be a good dissertation."

The system has adapted to the modern norm, with many students not offered tenure-track positions. Colleges and universities often offer temporary positions that usually last one to three years.

"It's a kind of academic proletariat," Steven H. Biel, director of studies in history and literature, says of these "adjunct professors."

"Increasingly, colleges and universities--and Harvard isn't among them--are cost-cutting but essentially exploiting cheap academic labor that they don't have to pay real salaries or benefits to," he says.