Oracle GoldenGate 12c offers new data delivery features that have enhanced the Replicat through integrated or coordinated modes. Manually adding Replicat process groups to improve performance is valid for classic mode. For integrated and coordinated Replicat, we no longer need to adopt the @RANGE function to partition data for delivery because it is Oracle's best practice to allow the apply server coordinator to autotune parallelism.
The GoldenGate documentation states "The most basic thing you can do to improve GoldenGate's performance is to divide a large number of tables among parallel processes and trails. For example, you can divide the load by schema".
In earlier versions of GoldenGate the bottleneck was due to the serial nature of the Replicat process having to replay transactions in commit order. This is still true, but given the automatic parallel apply processes that are available in integrated or coordinated mode...