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with perfectly well lit i have meant that the balance of more space being well lit is given, something you dont have on an "average" day. of course that also depends on where you are standing, high buildings can potentially take away the balance of it.
These don't really make sense.
In #1 if you decrease ISO to a lower number , increase shutter speed to a higher/faster number and do not change aperture everything is going to be less exposed (darker) than one wants.
If you decrease ISO then you need to either/and slow shutter speed so it lets in more light, or increase your aperture size to let in more light.
# 2 When you talk about shadows, whether from harsh light or not, you need good dynamic range of the camera to pull out shadows in post processing. LightRoom allows a good method to bring up the exposure of shadows in all, or selective areas. I do this all the time.