When I learn a new character, I often find it helpful to write it many times fast, to get the "flow" of the character. It would be really helpful, when encountering a new character or making an embarrasing mistake on a review, to be able to quickly "zoom in" on that character in some sort of quick scratchpad.
It could just have recognition for that particular character, without tone entry. When complete, the character could clear out after a split second and be ready for writing the same character again. Maybe even a counter, so I could see when I had done 20 reps or something.
It could be a modal toggle I could enable to "muscle memorize" and then toggle back to continue the normal practice.