I'm sort of having trouble seeing how it seems a lot of people have such problems with cooking turkey. The cooking time for poultry is 20 minutes per pound at 350 F regardless if it's chicken turkey, duck, or goose. So a 20 lbs bird would take about 6 hrs and 40 ish minutes, 15 lbs bird would take 5 hours, a 6 lbs one takes about 2 hrs, a 3 lbs one about an hour. If your not sure of the time, the easiest method I've found is to take the poundage and divide by 3, this gives you the hours easily.
You just have to make sure that 1. the bird is completely thawed before you prep it the way you want without over stuffing it, then it goes in the oven, 2. that you cover it up and leave it the heck alone (repeatedly checking on it lowers the temp of the oven and the bird), 3. about 10-30 minutes before the time is up (depending on the size) uncover, give a quick baste or I like to rub a stick of butter over it quickly, 4. pop it back in the oven for the remainder of the time, 5. take out, cover it back up and let it sit for at least 30 minutes, 6. you're ready to carve.
I rarely use a meat probe. I can usually tell if it's done just by looking at it/smell or I pop a very small hole in the bottom of the thigh skin, if it is still even slightly pink, it goes back in the over for 20 more minutes. I've never had dry turkey, but if you do end up with some that is drier than you like just arrange the meat on a plate, spoon some of the juices on/or warmed up chicken broth, and let it sit for a couple minutes.