Just give us Manual Overide ...
I get tired of Flux guessing my work schedule and bedtime. Just give us three manual push buttons - in the menubar icon would be good - Daytime, Sunset and Bedtime. The Brightness slider in Prefs would still set each one, like the Custom Setting, but don't auto-conrol when they transition.
So many of us work strange hours these days. A scheduler would also be a good, simple answer.