Last tested: Aug 23, 2019
Let's assume that we have 3 nodes. When a user logs into a clustered environment, they'll hit a load balancer that forwards them to a node in a round robin fashion. New users and schedules are auto-distributed across nodes.
For the per-user-query-limit, a user can still only simultaneously query 15 queries at once because Looker does not distribute connections across nodes.
For the max connection, there is still 70 connections per node.