My theory is if you hit 4 key days/year you’re always good. Summer Solstice, Winter Solstice, Vernal Equinox, and Autumnal equinox.
June 22 is tough i. Northern Indiana as it is about as far west as you can get in the eastern time zone.
Discussion
I've never considered that. I got my night rating for rotary a couple of years ago and flew during autumn just before the sunset. Twas nice. 🤩 Haven't flown at night since.