Yeeaaahhhh..... Seriously not seeing your point. I assume you're taking highways with higher than 55 MPH speed limits. The funny thing is, the time savings LESSENS at higher speeds:
Going 70 in a 60 zone saves 8.57 seconds per mile.
Going 75 in a 65 zone saves 7.38 seconds per mile.
Going 80 in a 70 zone saves 6.43 seconds per mile.
Going 85 in a 75 zone saves 5.65 seconds per mile.
Going 90 in a 80 zone saves 5 seconds per mile.
Going 95 in an 85 zone saves 4.46 seconds per mile.
I don't know of any places where the limit is above 85, so I'll stop there.
But you say you can save an hour... so:
If the average speed limit is 60, that's 19 hours instead of 20 hours.
If the average speed limit is 65, that's 17.46 hours instead of 18.46 hours.
If the average speed limit is 70, that's 16.14 hours instead of 17.14 hours.
If the average speed limit is 75, that's 15 hours instead of 16 hours.
If the average speed limit is 80, that's 14 hours instead of 15 hours.
Looked at in the overall, I don't see much advantage, to be honest. And you'd have the added peace of mind of knowing there's NO CHANCE of getting a speeding ticket.
Drive safe, my friend.