When you get directions from Google Maps, do they assume you're driving the speed limit?

For example, if I get directions from google maps, how fast do they assume i'm driving? If it estimates my highway trip to be 3 and a half hours, is it under the presumption that I'm going 65? Should I expect to arrive earlier than the estimated time if I usually average between 75-79 on the highway?When you get directions from Google Maps, do they assume you're driving the speed limit?
They also consider traffic so you could be faster without speeding.When you get directions from Google Maps, do they assume you're driving the speed limit?
They go by the posted speed limit on every section of road

I seriously doubt if you average 75-79 mph on the highway

If that is indeed the case then your mean speed is in the 90+mph rangeWhen you get directions from Google Maps, do they assume you're driving the speed limit?
Yes they go by the posted speed limits so if you speed and don't hit rush our Traffic you should shave off a few minutes.