The only thing that's strange to me is that the "default management server" is within the live update policy settings.
It can see where that would be a little confusing; I suppose a more apt name for the policy would be LiveUpdate/Content Delivery Settings, but that gets a bit wordy. (Which version of SEP are you using?)
Since the clients will get new content from the SEPM if it is available whenever the clients next check in, I suppose you could alter the SEPM's schedule (as SebastianZ notes above) from the default of every four hours to something like 3pm. (Unfortunately, a multiple-daily schedule, specifying soemthing like "Check at 8am, 1pm and 5pm," is not an available option.) Clients continue to check in and upload logs, but they don't get new content until the SEPM gets it.
However... I don't think I'd do this. SEP virus definitions are updated three times a day, and for security reasons clients should get updates as soon as they can. Also, more frequent updates equal smaller delta files provided to the client, instead of less frequent, larger delta files.
sandra