We learned a lot, which is why now whenever we hear that advice, we laugh at whoever believes it.
Guineas are feral, loud & not bright.
We had a chicken pen on the east side of the barn we built. Because we had raised them there, they continued to roost on top of it after they were turned out to do the tick thing.
At whatever point in the afternoon the sun created a shadow over the pen and one of the guineas happened into the shade, it would immediately assume night had fallen, and call all the others to come roost for the night.
Once this started, it didn't stop until all the guineas were roosted. Occasionally one would stick its head out into the sun, declare a new day, and wander off, starting a panic in all the others until they either all followed it out into the "new" day, or it came back to roost.
This story is for everyone who is startled by the fact that the time change results in sunset happening at the time it's supposed to happen, but has been delayed by DST.