Well, a few things, first any online map assumes you'll never have to stop or slow down for food, fuel, or any other breaks, so they are always going to be very optimistic.
Second, even if that was accurate, 7 hours in a car is draining. To expect that after you've woken up early to get out on the road, that you're going to be up for a lot of siteseeing is just not that realistic. You're also not factoring in that you'll need time to get your campsite, set up and tear down. If you're going to be on the road at 7, you're going to have to be up at dawn to clean up, tear down, and pack up.
And Finally, ignoring all of that, I just don't see where you got that 7 hour figure in the first place. Many of the legs you've listed would be well over 7 hours, even by the very optimistic Google estimate. For example, Redwoods to Santa Cruz is 8 hours via google, El Paso to San Antonio via Carlsbad google's out at 12 hours. And others, like Anaheim to Vegas or Vegas to Grand Canyon, while fine in a vaccum, become impossible when you're planning to See Disney, Vegas, and GC over the course of 3 days.
As far as what to cut, the obvious would be Texas. Simply removing Austin and San Ant. saves you 1000 miles of driving, if you just went from El Paso north to Texas (dropping El Paso and exploring Colorado directly from Grand Canyon would also save a lot of miles). I'd also cut out Canon City, but that's simply because I strongly dislike Royal Gorge and think its one of the worst, most expensive, and poorly done tourist traps I've ever been too.