Information about SETs and task-time

Hi Everyone. I've been tasked with giving a short presentation at our next department meeting about SETs. I've given such talks in the past (this is not my area of expertise) but one bit of data that I thought would be interesting to include this time around (aside from all of the reasons to think that SETs are bad measures of teaching effectiveness but decent measures of student experience) is how much time students spend on online evaluations.

I can't seem to find such data, however, and was wondering if anyone here knew of any studies that included or even looked at task-time when it comes to student evaluations of teaching. Anecdotally, my own students tell me that they zip right through them, but I'd really appreciate actual data if it's available.

Help?