TNJAKE, my apologies that I misunderstood your statement above.
I stopped logging smokes this year, but looked at last year's log. 1/7/18, smoked a 19 lb turkey, spatched using a combination of lump and briquettes. I used a big, round paella pan with a cooling rack in it to keep the bird out of the juices and allow circulation (I always use some type of pan to catch the juices for gravy and keep the smoker cleaner). My target chamber temp was 325F, but the smoker ran at 354F. It was a 4 hour and 5 minute smoke for the bird to reach an IT of 167 in the coolest part.
Next bird: 18 lb spatched bird, chamber ran 350-365F. Bird took 4 hours to 165F IT.
Next. 18.3 lb fresh bird, spatched, not brined, took 3 hrs 15 mins at 325F. (Go figure. Birds are as ornery as pork butts).
Three days later I did another 18.3 lb fresh bird, spatched, but the smoker was loaded with a big pan of veggies on the lower rack. The veggies were a huge heat sink with the bird because there was almost a full bottle of cheap white wine in the veggies. Smoker ran 250-280F and that bird took 4.5 hours to finish.
Two lessons. Smokers can be ornery, and there's nothing linear about using a smoker. Also, it generally takes roughly an hour for a bird's IT to rise from 140F to 160-165F IT in the coldest part when the chamber temp is 325F.