For "round robin" DNS usage, wouldn't a lower configured TTL (time-to-live) of 0 be preferable?

Yes, a TTL of 0 would be best for clients that are efficient with their DNS queries. We recommend caching DNS query results on the client to limit the number of DNS requests.

Most operating systems (Windows XP, Windows Vista, and UNIX [with nscd daemon]) will cache the DNS query results from client processes. You may notice that even with a TTL of 0 seconds, some clients will cache a query result for a few seconds. This means that multiple threads running on the same client may go to the same initial node because of a system-wide cache on the DNS query.