I'm not entirely sure I understand what you're trying to do, or why this is in the User Manager forum.
If you're trying to balance an arbitrary number of people onto 3 address lists for one hour based on their source address use PCC with a time out something along the lines of the below would probably work:
/ip firewall mangle
add chain=prerouting in-interface=LAN per-connection-classifier=src-address:3/0 action=add-src-to-address-list address-list=list1 address-list-timeout=00:01:00
add chain=prerouting in-interface=LAN per-connection-classifier=src-address:3/1 action=add-src-to-address-list address-list=list2 address-list-timeout=00:01:00
add chain=prerouting in-interface=LAN per-connection-classifier=src-address:3/2 action=add-src-to-address-list address-list=list3 address-list-timeout=00:01:00
It's not going to be exactly round robin, but the more IPs are online the more even the distribution will be. Could be improved in some ways but I don't think there's enough details in your request to start on that yet.