Late finishes have been a talking point in tennis for a while now, but it's been a particularly big topic this year. Many players have started to push back on the late starts and subsequent late finishes because there is very little benefit to them if you're a player.
There are plenty of benefits if you're an organizer or the ATP, but ultimately, it's just not what the players want. At some point in time, you have to listen to your players because, in the end, there is no product to sell without the players.
What's particularly egregious is that Sinner was scheduled to play the 4th match of the day schedule instead of at night, giving him very little time to recover properly. Ruud was no fan of that, and he bashed the ATP on X for it.
Bravo @atptour way to help one of the best players in the world recover and be as ready as possible when he finished his previous match at 2:37 am this morning 14,5 hours to recover.. what a joke
It's not the first time that something like this happened, and it's pretty clear that players have had enough. In any case, Sinner didn't even play that match. He alluded to the possibility of withdrawing last night and ultimately did that earlier today, citing fatigue.
He likely could have played that match, but with the ATP Finals so close, there was very little reason to push himself too much. It's better to rest up and prepare for that event properly than to force yourself to play on short rest.