Originally Posted by dward51
One other point I would make from my experience. Seems if I'm doing 1 butt or 6, the time is about the same. The meat mass mostly affects the time it takes for the smoker to recover from opening and initial start up. As long as your heat source is up to the task, I don't think meat mass makes that big of a difference in the overall cook time. You will burn through fuel quicker in a charcoal or stick burner trying to keep the temp where you want it with more mass, but again as long as the heat source can keep up, I don't think it really matters how many butts you are smoking time wise. Since you are using electric, there is no fuel source issue to worry about as long as the element is up to the task (and it probably is). No scientific facts to back me up on this, just my impression after years of smoking various numbers of butts in my 18" WSM (usually 4 at a time - and I do use a Guru power draft so fire temp control is spot on). Mileage may vary in another smoker or one set up differently (no power draft).
You are absolutely right, for the most part. 225 is 225, regardless of how much mass is in your smoker Recovery time when adding the meat will definitely be affected. And it will also require more fuel, ie. more heat to bring the chamber back up to 225 and hold it there.
Something very important though is that most smokers do not have consistent chamber temps throughout. The temp on one rack will be different than the temp on another. With vertical smokers, as you load the racks up, the meat on the lower shelf will act as a heat baffle. For example, my SH44 has 5 shelves and when fully loaded, there can be quite a bit of temperature difference from top to bottom. Meats on the upper shelves will simply take more time to cook. For the most part, your options are to either accept this and plan accordingly, or, rotate your items during the cook. Even then, it will still take more time overall than it would just to cook 2 butts sitting on a single shelf.
Can't speak to the WSM as I've never cooked on one. Perhaps Weber found a way to more evenly distribute the heat no matter how the WSM is loaded ?