I actually use "Night Shift" all the time in - even in highest settings (strongest "yellow").
It filters almost all of the blue lights out of all colors, not just from white areas.
Sure, this needs a day or 2 to get used to it, because at first your screen appears WAY to yellow.
But then (to me) it looked normal - the big surprise comes after a week using your device that way:
Especially at night, when you turn off Night Shift manually for a second - you will be shocked how colder colors will hurt yours eyes. Really recommend trying it yourself.
By the way it will also save a litte battery because "blue-ish" colors need more energy to be displayed.
Reason:
The frequency of blue colors are way shorter, it means blue pixels need more energy appear as bright as other (warmer) colors, like green or red. That shorter frequency of blue light is the reason why NightShift exists in first place - wave lengths of blue (cooler) colors are that short that it passes trough cells itself, what might can cause cell damage. That's the theory behind it.