As I understand it, the 50% rule is just about drawing for the sake of drawing - if you're drawing from life as an exercise in practicing a specific skill set or building out your visual library, then I would consider that deliberate practice and not part of the 50% rule. If you're drawing from life just because you're in a cool place and you're having fun drawing what's around you (and the result of how it turns out is not the focus of the drawing) then I would consider that part of the 50% rule.

The point of having multiple references is to help avoid copying any one specific reference, and instead pulling information from what you can see in front of you. If you're having fun trying to copy a scene exactly, then that's totally fine - ultimately, the 50% rule is about learning to have fun regardless of the outcome. If your piece turns out poorly and you still enjoyed the process of making it, then you're doing the thing.

At least that's my understanding, anyone else please feel free to correct me. Good luck!

I'd argue drawing from life to be more than one "image" because you are free to change your PoV, pick it up and move it around, to help you get a better understanding of your subject.