When I was finishing grad school, my department instituted a "3 paper option," which allowed students to elect to write three papers in lieu of a dissertation. The papers were supposed to be of such a quality as to be publishable in a top-tier journal, and were expected to be related in some (at least) loose way (e.g., three papers on realism-- one in phil sci, one in metaphysics, one in ethics). This seemed to me to be a good idea at the time because many of my classmates were working on topics that were developing so quickly that their first dissertation chapter was obsolete by the time they'd finished a draft of their second chapter. The option also enabled students to finish their degree with three stand-alone articles to submit. But I suppose there are drawbacks.
Anyway, does anyone out there have any data or insight regarding the wisdom (or not) of the 3 paper option?