Most simply use the system clock. Now if I would was building a machine critical distributed system I would advise against using the system clock and instead us

Most simply use the system clock. Now if I would was building a machine critical distributed system I would advise against using the system clock and instead use some sort of logical clock. But in this case the clock doesn't need to be super accurate, it just needs accurate enough it get placed near the end of the table. But the worst case in this instance is your insert is slow, and fragments your index. I trust infrastructure to make sure the clocks are accurate.