You can save the output of a function for use in the pre- or post-process scripts for functions further in the workflow. You do not need to save the output to use the result in the post-process script in the same function.

The output from a function can only be used in its workflow; it cannot be used in the workflow’s child or parent workflow.

You should not save the output if you do not intend to use it at all, which allows the platform to conserve storage space in the workflow.