I'm not an Ethernet expert, but I think you're conflating the Time To Live (TTL) value with the 5-4-3 rule.
As I understand it, the TTL value is decremented by routers, not by switches or hubs. You never see it decremented when you are diagnosing a small LAN.
I will postulate that if you had an infinite set of hubs, connected with uplink ports, that a packet would continue to travel from hub to hub indefinitely. The signal is re-generated at each port, and there is no TTL decrement that would cause a hub to not send the packet on.
Before we spiral into a debate or discourse, I think we should take a step back and have Stu explain some more about his question.