people do it all the time you'll be fine

Exactly. You would have to do this several times to stress your plants.

I just changed my lighting from 18/6 5am to 11pm down to
12/12 9pm to 9am with no noticable problems.
This was mainly due it being summer here with daytime temps in the mid 30C's.

i once heard someboday say "there are always storms and dark days with nature". light is changing all the time. gardens, bushes, trees get in the way. or maybe one is admiring a plant so beautiful that they stand unrealizing infront of the sun for an hour.

you can switch up a few times but not a ton like CR8Z13 said.