Snoozer, yes really. Take a group of mythical skygods and gun controllers of yesteryear and there was still be a spread of skill levels. Everyone has days they'd rather forget performance-wise and events they learn from. That is the systemic envelope we all operate within. Or does nobody ever go around due to something they've stuffed up or never overcook the spacing between aircraft in a sequence in your world? No, I'm not saying it's as efficient as it could be, but at some stage no matter how much you jam 'em up you run out of capacity sooner or later if too many try to arrive within a given time.
You might be able to nail the fix time to 10 seconds from a 1000 miles out, fantastic. But it just doesn't work well in the real world when there are more than a few aircraft in the sky. Do they actually use that as a sequencing technique anywhere in the world?