When should you use the nrf_pwr_mgmt module?

I'm reading the SDK15.2 documentation coming from SDK 11.  I've noticed the nrf_pwr_mgmt module, but I haven't seen it utilized by any of the examples.  When should this module be used?  It seems like its not required for Power Optimization, so I'm a bit baffled at to its purpose.  

Cheers,