Unfortunately with a phone that has so many configurations, some seem to benefit while others don't and no one has the patience to run down the differences to see what's eating up what.
In my case, it serves no purpose. I have everything on and I still get 18-36 hours depending on how much gaming and desktop website (instead of mobile optimized) surfing I do.
Samsung Galaxy S® 4 MJA Rooted with CF Auto-Root Tutorial
HTC EVO Design 4G™ v4.0.3 Bootloader Unlocked & Rooted with HTC SuperTool v3
If it ain't broke, use a sledge hammer.