How much portfolio material is too much?

https://mitadmissions.org/apply/firstyear/portfolios-additional-material/

“Visual art & architecture
Creative individuals with exceptional talent are welcome to submit a portfolio via SlideRoom.”

http://web.mit.edu/fnl/volume/282/peterson_abelson.html indicates that in 2014, between 3% and 11% of applicants submitted any one portfolio.

I suggest only submitting materials likely to be impressive in that context.