By default, the maximum number of data and log jobs will each be set to 1, when job throttling is enabled for the client.
By default, the jobs targeted for immediate execution are not excluded from job throttling. All RMAN application command line jobs are immediate jobs. However, you can exclude immediate jobs from job throttling. This is useful when the administrator wants to run a backup immediately without waiting for the queue to clear even when the job limits have been reached on the client. In this case, only scheduled jobs are throttled.