How long does it does for video ratings to update?

I always figured they updated instantly, but I bought a bunch of ratings for some videos and when looking at my videos from my personal profile, I see the star rating at 4.5/, yet on the video itself where everyone can see it - the star rating is only 3/5. How long does it take for Youtube to reflect these changes?

Something like around 8-12 hours or so (haven't counted the hours but it seems that way).