Mike In ceramics often things work until (even thought not done right) until one pushes the limit -such as your fast fire.
It does matter that all posts are under one another from the floor to the ceiling. You may get away with this for years but sooner or later it will get you .
Wadding is EPK and alumina hydrate mixed 50% 50% with a little water.
next time make sure all pots including under floor all always lined up-the wadding as on under floor pots only to level. fire the 1st time a bit slower to dry wadding .
I will speak to your pots layout only after I know what you use above that full shelve ? all full shelves or some 1/2 shelves??
We use full rounds all the way up the stack. We use to use halves, but when I'm firing a full load of Rocks cups, I need every single cubic inch I can get. We use a 3 post arrangement between shelves. In bisque I allow a 1/2" space between the rim and the bottom of the next shelf, except when I get to the thermocouple. I make sure there we have enough vertical space to provide 2" of clearance on all sides of the thermocouple.