Frankly speaking I dont know. But I feel it will be an additional overhead which you will be putting by calling it repeatedly. The reason is that we would not have enough number of images to be processed simultaneously so the parallelization setup cost will be more. I feel we must do it only if our batch size is 64 or above. But setting up such a batchsize  depends on our available resources.
However for my post processing I never used parallel execution.