Fortunetaly, I don't have any horror story. My life with Vue is very "peaceful". :-)

But I'm intrigued why is it 12 hours "huge" for you? If it fits more or less within one night, that's fine, IMO. Normally, I try to finish the scene just before going to bed or going to work, hit the render button and when I return, the render is finished, or I have to wait just 1 or 2 hours more. So, 12 hours seems fairly ok to me. 

In fact, if I have a render that lasts less than 8 hours, I feel it's a waste of processing power because the computer was just sitting there idle all that time while I was sleeping. :-)

In order to fit within the time I have, I change the render settings, watch the forecast duration, adjust render settings, watch forecast duration, until it fits more or less.