If you’re seeing high cluster waits because you have multiple processes all inserting into the same set of tables, the cluster waits are resolved by pointing to a single node on the cluster. But just pointing to a single node defeats the rollover benefits of running on RAC. To that end, Oracle gives us Services to assist with workload management. It’s a TNS entry that prefers a specific node, but will use a secondary instance if the preferred is unavailable. So all processes that use a common set of resources can all be pointed to the same instance, eliminating the cluster waits.
In practice I have seen this improve performance by 500% on high volume inserts, so definitely a feature worth checking out.