It's pretty hard to drive in a straight line in the UK though, so even though it's 600 miles from John O groats to Lands end, it's actually 840 miles of a drive. Longer if sections of the M6 are closed.

But, I do agree with you. Driving 400 miles here from Edinburgh to Southend is not a straight 400 mile motorway drive at 75mph like it would be in the US, it's practically guaranteed to hit standstill traffic at one point or another. I'm sure you technically _could_ do that journey in one sitting in a car, but the vast, vast majority of people will be pulling over to break, even if it's just to the bathroom.

I drove from Edi to Cornwall , which is about 550 miles. We stopped twice on the journey, once for a coffee/toilet break (15 minutes by the time the coffee was made and we had queued for the toilet), and once for food (45m). Adding 1 hour onto a 9 hour drive was not a deal breaker, and if it was then we wouldn't have made it on time because we were also delayed by numerous breakdowns, accidents, lane closures, horses on the M6. We lost more time to all of that than we did to rest stops.