Perhaps we're using different terminology, but it's absolutely not customary to assign a /64 to each machine. IME one advertises one or more /64's on a given n

Perhaps we're using different terminology, but it's absolutely not customary to assign a /64 to each machine. IME one advertises one or more /64's on a given network, then (either through DHCPv6, or SLAAC [or both]) machines attached to that network acquire addresses within those spaces. These machines will have a XXXX::XXXX/64 address, but that just means that they're attached to a network that advertises a /64, not that that machine has been assigned an entire /64 for its use.