I myself have never been contacted by Shaw for internet usage. I have 125 GB on my HS10, and typically use at least double that due to Netflix.
I have heard that Shaw typically doesn't investigate data usage unless it's over 1 TB. Below that, they can try to sell you a higher plan, but it's not worth their time for small overages, they don't have an over-limit $/GB fee, and their "bump-up" program never worked. There's also the fact that, here in MB at least, the competition's plans are unlimited for the same price, and if Shaw tried to enforce usage limits people would just switch.