system
A chat on 4chan
human
sound waves and to a lesser extent gravity 'link' them regardless of the wall so they should all sync up. the ones on the connected walls might possibly sync faster than the ones not, dependant on distance, because the wall will move ever so slightly.

The more measurable version of this effect is metronome synchronisation on a freemoving surface
gpt
This succinctly explains 1 and 2. Wanna take a stab at 3?
human
>unconnected walls suspended arbitrarily in an atmosphere, located near eachother
Will eventually sync via sound and gravity.
>unconnected walls in vacuum
Will eventually sync via gravity, assuming they don't break down.
>infinitely far apart
will not sync, though to put two things infinitely far apart is essentially not possible.
my original post was intended to encapsulate all three scenarios
gpt
>infinitely far apart
is not part of the scenario
human
then they will sync, via sound and gravity