I don't know the name of the effect so searching the uesp didn't help. I've had this effect on for over a week.

Are you talking about the Favor of Akotosh? It lasts for 86400 seconds, which is a whole actual day (not game day.)

True. It lasts for 24 real life hours. It's fortified Personality and Luck, not a terrible reward for completing the main quest.

I think so. Got it from the new dragon in the temple of the one. And have had it for a couple of weeks in game and out. Noticed it stuck at 1/2 for awhile and then activated the statue again. Now stuck at full.

edit: just went back into the game and removed my equipment (and don't have any spells up). The only effects that shouldn't be there are the favor of Akatosh. I don't know if it glitched the same way but had the effect of the boots of springhel jak permanently on from having those boots on when I slept to do the "through a nightmare darkly" quest.