Not necessarily. It's not so much that a 10-second delay will be introduced at every repeater, but that a practical system/implementation requires that a delay

Not necessarily. It's not so much that a 10-second delay will be introduced at every repeater, but that a practical system/implementation requires that a delay of up to ten seconds may be introduced when required by traffic, etc. A straight-pipe, latency-free, synchronous-only system would require a lot more infrastructure to support (analogous to the earliest direct-connection telephone systems).