Don J. Modesto wrote:
What say you? When can one actually shift the prescribed technique?
I would say, It depends...
In the daily training environment of my own dojo, students are not advanced enough to be able to apply henka-waza at will. Some of the yudansha are, however, and are at liberty to do so, except when participating in classes for beginners. Then it is the rule to do the waza being taught.
For me, henka waza are not oyo waza. They are specific techniques, which then become other, quite different techniques. A master at this sort of training was Seigo Yamaguchi, who would sometimes execute a waza almost to the point of ukemi, and then do something else quite different. It was very good for learning ukemi skills.
I think this training is good when tied with kaeshi-waza and when the line between uke and tori is so blurred that roles can be changed at will.