> No you cannot, unless you're running a single threaded server process on a single machine. What you can do is _gamble_ that you probably won't have a collision

This seems like a pointless distinction.

If I did the math right, you can generate 1,000,000 ULIDs per second (1000 per millisecond) for around 50 million years before you can expect to hit your first collision.

I don't know about you, but I'm pretty sure any system I build won't be running 50 million years from now. Not to mention that the timestamp portion of the ULID will overflow in a mere 9000 years.