I found that those had one continuous spiral crack running from 1" from the bottom all the way up to 1" from the rim. Like a spring! Hmmm. after lots of research, and talking to others including the folks at SC clay, I changed my firing schedule and had no problems.
Sometimes not all is a disaster, and a little help and research might help.
When I was doing engineering we "stressed to failure". That was the ONLY reliable way to see how far a limit could be pushed in a real world situation. We pushed the limits till it failed... re-tweaked and tried again. Failure is absolutely essential... just as long as you are in a position to set things up so you learn from it... like Pres.