I've got two cast iron offsets one weighing in around 450 lbs and the other 700 lbs or so and once I got them set they have not moved in 4 years now. Crazy question, but for those of you with big cast irons how often do you move them, and why? Or, do you get them set for prevailing draft and just leave them? Is prevailing draft the primary reason you move them? Thanks in advance for your input .....