When I was in university, I shared a house with a bunch of friends, we paid for 30Mbps, then I set up a router with nice cache system, QoS and all that stuff.

Most of the days we used around 100GB+, our isp called sometimes (two months interval more or less) to say that we hit our monthly data cap (which was 320GB), we got used to saying "ok, so cancel my plan, we are going to another ISP that don't put cap on our data usage" and then they continued the conversation saying that "this month we will not reduce our speed, but next time they would have to, unless you upgrade your plan", "no, thanks".

Since they were a new provider in the region, guess that the infrastructure were more than enough to sustain our use, and I was really surprised that the same excuse worked for around two years (then I graduated, don't know how it's now).