When I used my chargriller, kettle, and wsm at my first comp Im guessing I took 30 lbs of lump plus wood and had just enough. In the chargriller I only cooked ribs because the wsm did the overnight work useing maybe 10-12 lbs. Kettle cooked the chicken so that was only a couple of chimneys. We cooked brats and other meats on the kettle that we shared with folks so that totals about 20 lbs + or - a lb or 2. So I guess I used 8-10 lbs of lump cooking ribs.
One thing that I have learned is take extra fuel. It keeps forever as long as it stays dry.
Spicewine Turbo 2007 model
Perry Brothers & Sons Bar-B-Q