Expected traceroute behavior across unequal length multiple paths

I'm helping to troubleshoot what I believe to be a red herring. The scenario is that a customer is complaining that traceroute to 8.8.8.8 doesn't always terminate at the destination node. Often, the last hop listed in the traceroute output is a combination of 8.8.8.8 and one or more Zayo IPs at the Google peering edge. If I use '-q 1' to force traceroute to use a single probe rather than the default three, it always completes at 8.8.8.8, but the hop count varies from 5 to 7, depending on the path for that particular probe.

I guess what puzzles me is more a question of expected traceroute behavior. It appears that a default traceroute is terminating any time one of the three probes end at the destination node. I would hope that each probe would continue to completion, even with paths longer than the minimum. Should I expect that traceroute always ends any time it receives a response from the destination, or when all probes finish successfully? As with all things, I wouldn't be surprised if the answer is "it depends", lol.

Edit: Clarity