[jeremydeanlakey]

To make this more concrete:

If your service layer method requires data to be saved and the results to be sorted, you want to call a data layer method that saves it and a library method that sorts it. You do not want any of that saving or sorting functionality in your service method.

Combining different layers and different tasks so that your module is "deep" rather than "shallow" will make your code much higher cognitive load and create a lot of bugs.