You’d be surprised how often intelligence analysts use those books.
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In WWII when the Nazi Subs were patrolling the East Coast like they owned it, the U Boats would use the lights of Miami, Atlantic City and the other beach ‘resort’ areas to attack shipping which was hugging the coast line.
It took a lot to get those people on the Coast to ‘turn off the lights at night’..
Also, Capt Reinhart CO U123 transited Long Island Sound - using an Esso road Map to navigate - along with the lights. They made it into NY Harbor...
From Wikipedia, ref “Operation Drum Beat” good data on the 1941-42 times on the East Coast
https://en.wikipedia.org/wiki/Second_Happy_Time
I know someone who lived in NYC at the time (WWII), and he recalled that the blackout ostensibly to prevent the silhouetting of ships was actually to prevent NYers from seeing the ships damaged by U-boat attacks limping into port at night. Our government never told the public how bad it was during “Drumbeat”, but some things couldn’t be concealed; IIRC, off the Florida coast sunbathers watched a U-boat on the surface sink a ship off the beach - and the U-boat was between the beach and the ship itself.
I believe German subsidiaries of American insurance companies could also access information on the cargoes of specific cargo ships as well; some of the officers of torpedoed ships were shocked at how much the U-boat officers knew about the ships they were sinking...