But, unless you have multiple users on your network simultaneously, you'll rarely, if ever see downloads anywhere near 600 Mbps. High speeds are great for bragging rights but are of little utility for most folks usage patterns.
Telus technicians consider your Internet to be 'working' if your download speeds are with 75%. For example, 75% of 75 Mbps is about 56 Mbps. So if your download speed is 56 Mbps or better, they don't consider anything to be wrong.
I don't know what Shaw's policy is.