|Note the difference in the depth of each stance|
There's a strongly held belief in some karate circles that things like stances have to conform to a particular set of measurements to be correct. I've seen training grind to halt many times when I practised Tani-ha Shito-ryu, while the teacher moved a student's foot half a millimetre this way, or a leg was nudged a fraction of an inch that way.
I'm not suggesting stances are not important in karate, quite the opposite in fact; make a poor foundation and the techniques you try to use are almost guaranteed to fail, or at least, miss their full potential. No, a well made stance is vital for the delivery of effective techniques; but what makes a good stance? For me that all depends on what your intention is.
I've long believed that principles outweigh image when it comes to balancing form against function in the execution of karate; get the principles right and the technique will be correct...even if you do happen to look "different". The idea of perfection as far as karate techniques go is a myth born, I believe, from a kind of arrogance that many humans suffer from (especially alpha-male karate types), leading them to believe they can control just about everything.
Karate is understood best through the principles it is based upon, not by the techniques you are able to remember. In the rush to be a karate teacher, don't forget to remain a karate student.