Would More Permissive Split-sleeper-period Rules Allow Drivers To Get Better Rest?

Well the 70 hour rule has to be there because you have to limit the total driving time someone can do beyond just the daily limits. Otherwise people would be able to drive 77 hours every 7 days instead of 70 hours every 8 days. That may not sound like a huge difference, but it is. Once you get up around the 3,000 mile per week mark you're getting to the limit of what most people can do safely. In 77 hours of driving you could hit around 4,000 miles a week and that's just entirely too much.

They've tried to set up the rules where you can put in some really long days from time to time but soon after you're going to have to get some extra rest, thus the combination of the 11 hour and 70 hour rules.