85 is hard on the parkway during a busy time but on some of the 65mph interstates (ie, 78, 287) you can get long stretches of 85mph, especially during somewhat off-peak times. I kind of agree with what you're saying with the time save, but you usually average a few mph slower than your top speed on the whole drive, so 80-85 is often worthwhile so that you can average high 70s.