The way most countries do it, the sleeper runs at whatever speed, and then just gets shunted to an out of the way platform, and the passengers have to disembark by a certain time. But - and this is the key difference - anyone wanting an earlier start can depart as soon as they wish once the train has arrived at the destination.
Trains also don't get to take a very straight route... it goes west quite aways from central LA until it hits the coast, and then follows the coast north. It's certainly not HSR.
I find that mode of operation extremely disruptive. Part of the point of sleeping on train is sleeping on a moving train, and to sense at 03:00 or whatever that the train has stopped, permanently, destroys my ability to sleep.
UK. They have a lot less sleepers than they did 30 or 40 years ago though, when most of the main lines were limited to 70-85mph, and not the 125 the majors ones are today.
What they'd also do, on multi-stop routes, is arrange the passengers by destination, back to front, so when they hit the first stop they'd just uncouple the back car or two, then continue on.
Yeah, I mispoke with Dundee. The Caledonian runs to Fort William as its furthest extent, but also splits somewhere in Borders to get some carriages to Edinburgh.
Trains also don't get to take a very straight route... it goes west quite aways from central LA until it hits the coast, and then follows the coast north. It's certainly not HSR.