You can stay safely in game for 22 hours (23 is risky) but you gotta have 6 hours off after that. Simpler said, you're safe to be in the game as long as you have 6 offline hours in that statistic.
PS: this is not a bug
you need to have 6 consecutive hours online.
they removed that rule in the newer realms,so you can expect removal of that rule....and a lot of babysitters.