Yeah, just shy of 12 has been my formula for many years in my 3D. People keep paying me to cater their events/parties so it's working. Doing 12+ butts for an event this Saturday :-) I'm doing a test run of 2 butts tonight so we'll see if 12 still works or I need more for the smoke note I'm after.
Also gotta figure out how many butts I can actually fit in this 4 heh.