video on the same topic with a bit more explanation: https://www.youtube.com/watch?v=yBU6l6AVVss
edit: we had a few freak accidents with the machine. We’re not entirely sure why it happens. A 2000 block test went fine, but in another location the machine failed. After fixing the machine it covered another 1000 blocks without incidents. it seems like the armor stands sometimes don’t get properly saved, when they cross chunk borders. This probably is related to entities disappearing when crossing chunk borders. Mojang needs to fix something, before the machine works 100% instead of just 99.99%.
In this video we use the new and reliable version: https://www.youtube.com/watch?v=xvONs8Tov9Q
(it’s part of a bigger machine)