New to all this, but can follow instructions!
As I am in South London I got the smallest WSM, 18.7 inch
Using the minion method of hot briquettes on a bed of unlit on the grate I had the briquette ring filled up to its top edge.
All went well, stable temp etc. But after about 5 hours the temp was dropping, looking in through the door I could see ash had risen past the grate level and was snuffing the remaining briquettes. I tried balancing some fresh briquettes on those still burning to raise them out of the sea of ash but they never caught and I had to transfer meat to the oven.
It seems to me that there isnt enough depth between base of WSM and the grate to allow for the ash? Or did I get unlucky with my brand of briquette?