When working with color sensitive works (digital painting), I turn it off.
When working with 3D and CAD when color is not so important, I leave night shift enabled.
Personally, I enabled all this f.lux / night shift like features across my device, even on my Windows machine which natively supports it (called Night lights on Windows).
I even go further with set my surrounding working desk with yellow warm tone desk lamp. I quite night owl and find warmer light are more pleasant for longer working finishing deadline in midnight.