Ask HN: How long does it take for the "More" link to return "expired link"?

Not long enough, it feels like it's 5 - 10 minutes.

What's the benefit of doing it like that rather than a page=x or offset=x?

HN is written in arc, and many links point to thunks/closures ("if the user clicks on this link, run the following function on the current data"). IIRC, such thunks are valid until the memory is needed for something else.

So it depends on server load; maybe it's time for another memory upgrade.

It's usually around 15 - 20 minutes. Makes me feel like a bomb defuser, having to make sure to get to the next page before time runs out whilst working on other tabs.

It depends on server load, but 30 minutes will usually do it.