Maybe the instructor would have NEVER anticipated that this particular student would suddenly go off and produce a whole body of work with the untested reformulation and even plan on showing the work produced....... without taking all the knowledge that they already had about ceramics and doing things like the necessary TESTING WORK before ever doing such a thing.
I again come back to the fact that we have NO idea the context of this whole discussion.
I worked on this stuff over the course of weeks, 4-5 hours a day (6 days a week) in the same studio as instructor open studio AND class time . Sitting at wheels where we could talk and look each other in the eye. Even discussing the forms (he complimented me on every one of them) as I went. It's the yearly student/instructor show (so I know he knew I was working on pieces for it, we discussed it). In fact the pictured piece was fired in time for the show only because he announced there would be one final firing for it.
All my work isn't lost, I still have 5-6 on the shelf, change of plans, they just won't be glazed.
But again, I didn't go off on a wild tangent, I just didn't test with any amounts of feldspar. This is the first time I have formulated a body and I did it to his exact specs. (at least the ones he gave me). He watched me mix it, he had me test a coil for color (only), and I made about 10 test tiles with glazes (the test tiles haven't cracked). Then he watched me make 50 lbs of work and start mixing up another 50 lbs batch (as I still assumed his guidance was right) .
This isn't something I did out of sight, it was with his guidance right under his nose and the process lasted several weeks with everyone in the studio asking me about it, etc...He was well aware of every single thing I did regarding this process.
But at the end when it failed he said 'Well I do put 10% Feldspar in mine', 'You should have tested'.
The only way I would have known I needed Feldspar would have been to have my instructor tell me, or to second guess and look up recipies online and try to formulate myself.
It seems like you are still hanging on to this idea that your cracked pieces are the instructor's fault. Did you mix the clay or did he? Did you make the pots or did he?
If he mixed the clay and threw your pots, then yes it would be his fault. But he didn't, YOU did those things.
It is common knowledge to test before you proceed. This isn't just in ceramics, but in just about everything. Want to know why It is common knowledge? It's because if you don't know to test before proceeding, then you will learn very quickly because of mistakes like this. Thus it becomes common (moreover significant) knowledge to you.
Maybe the instructor didn't think adding feldspar was important? Maybe he didn't realize for some other reason, maybe he simply forgot. Big deal, it's life. Stop whining, blaming other people, and hoping for immediate satisfaction and perfection. Don't blame the instructor for your bad pots. That is entirely on you, fair or not.
Regarding your glaze popping off your pots--that sounds like shivering. I worked with potter S.C. Rolf when his clay/glazes were shivering. Huge splinters would pop off overnight and be laying beside the pot in the morning. The clay and glaze are different in that the clay shrinks a significant amount more than the glaze when cooled, which pops the glaze off in large pieces sometimes, especially around corners, edges, or points of major stress. Interesting that this might happen with a shino, as many shino's are high in clay and generally craze. Also note that one glaze may fit great after testing but another may still shiver. Glazes have different materials and chemical makeup in them and thus inherently have differing characteristics. This is common knowledge too so heed the warning.
Look here for more info on shivering. In this case it would probably be easier to adjust the clay body than the glaze. By the way, that shino you used looks fantastic on that clay body. You should share the recipe here for your fellow ceramic arts daily potters. Good luck with your clay body.