Many years ago, a lighting technician made a comment that stuck with me.
She said, “If we do our job right, nobody notices us. If we don’t — ooh, boy.”
And that is the reason for at least some of the anxiety that precedes the first tech rehearsal of any show.
How will the scenery look under the lights? And the costumes?
Different materials reflect and refract light differently and under bad lighting, to quote my friend, “Ooh, boy.”
Any bird watcher will tell you the same thing.