And in short distance unrepeatered coastal festoon fiber systems where it's within normal DWDM system reach, node to node with no active underwater electronics, those are also often in areas with relatively low population/traffic that won't need more than 8 or 12 fibers at absolute max on any leg in a chain or ring. Such as the Connected Coast project being built in British Columbia right now.

I'd be astonished if it runs into capacity problems with an ultimate upgrade capacity of being able to run at least 20 different 200 or 400 Gbps circuits per fiber pair if appropriately costly DWDM terminals are installed at each end of dark fiber. Not even if all the tiny towns and cities that it hits were to magically quadruple in population.