16 hours seems a little long..... I would verify your temperature and shoot for a slightly higher temperature like 250 to get the 1.5 hours per pound. Higher temperatures means an even shorter cook time.
Everyone has their own preferred cooking temperature, I've used 250° for over 20 years and it is second nature to me. I'm not willing to change at my age... don't fix what isn't broken. LOL
We must never forget that the highest appreciation is not to utter words, but to live by them - JFK