Day/Night time isn't linear between avatars

Both statements looks like 2 different things to me. You experienced only the first or both?
I also think the night is big longer than I expected.

 

Ah, yes, I see that now due to your statement.
It was intended as that multiple avatars don't have the same Time of Day. The linear part as in night taking longer than someone elses night, not sure haven't had a stopwatch with it to measure how long it took to change daytime/nighttime. So I can't say anythign about that but this could also be a cause of the different ToD's.

 

Dante is correct.
Same thing happened with me and my husband. Day for me, night for him. We noticed it twice but no idea how many times it happened when we didn't realize.

First time he logged off (was night on his screen), then logged back in to daylight so we were in synch. Second time it was me. Daylight was really night. Once again logging off and back in worked.