Yes it's best to start out with a full load of charcoal when you're looking at an extended cook. I always give the legs a couple of taps several hours into the cook to knock off the ash build up. This goes for both my Cajun Bandit and my WSM.
Lang 36 patio
18.5" Weber Smokey Mountain
22.5" Weber OTG with Cajun Bandit Conversion Kit
Char-Griller Akorn with side cart
1999 Weber Master-Touch - bent but not broken
14.5" Weber Smokey Joe Silver