Is there guidance on the setting for the number of parallel executions for Harvest Batch Loads?

When using the BRAPi.Utilities.ExecuteFileHarvestBatchParallel function in an Extender BR, does anyone have any guidance and/or opinions on the proper setting of the parallelBatchCount parameter? 

My understanding has always been to set it to a maximum of the number of CPUs - 1 , available for the server performing data management or batch load processing.