As with a lot you will find many opinions on this board about this. I'll offer mine. but it is opinion though based on research and my own long term experience.

I use the strips in a boolean manner. That is to say they turn or they do not. That simple. If they do not change I reflect to see the reason. If they do change I move forward. If they get dark it usually is because I just ate high fat or I am low on fluid intake. My goal is a slight pink as I know I am burning fat and I am fairly certain I am hydrated.