You got me curious...

I am around 1500 (actually 1649 on lichess blitz, but close enough).

I explored the last 5 games I played on lichess. Here are the number of moves before lichess had never seen that position before for each of the 5 games: 6, 12, 16, 15, 11.

> If you find yourself in a novel position within 10-15 moves it's likely a resignable one

The opponent is also going to be in a novel position. Should both players resign?

Just in case you think this is limited to low rated players like 1500s, look at MagnusCarlsen's most used account on Blitz: https://lichess.org/@/DrNykterstein/search?perf=2

You will see that most games become unique to the whole of lichess within 15-20 moves and a good chunk between 10-15.