I'm involved in a project that will be replacing a student information system at a post-secondary institution. I would describe the scope of this project as very large, comprising of approximately 200-250 known sub-processes (plus ones we currently don't know about yet), which are grouped into ~70 processes, which are in turn grouped into 14 broad process areas (e.g. Admissions, Registration). This single system will be used by students, staff and faculty across the entire student lifecycle. We are currently entering an initial requirements gathering phase that will last approximately 4-6 months. So this is our opportunity to engage in user research activities.
I believe personas are excellent tools for packaging up and sharing our understanding of target audiences. But almost all literature I've read (books, articles, etc.) talk about personas in the context of single-purpose systems or systems with a low number of purposes. It's not surprising then that much of that literature speaks to minimizing the number of personas you have (e.g. 3-5 distinct personas); that makes sense to me and I'd like to do that.
Yes, we have three core audiences - students, staff, and faculty - but these are far too broad to be useful as design artifacts. As a cursory example, international students have very distinct needs from domestic students. If I had 3-5 personas per process area, I'd be looking at something like 42-70 personas total. Is that reasonable, let alone achievable?
So my question is this: has anyone else here had experience developing personas for information systems with a massive functional scope, and if so, how did you approach persona development? How many did you end up with?