Reply: Most Taekwondo instructors have trained in, or at least been exposed to, other martial arts at some point during their martial arts formative years. They usually incorporate these arts into their Taekwondo curriculum. This may be good if the other art compliments Taekwondo (such as grappling) or it may be bad if the other art is contrary to Taekwondo’s methods (such as teaching the yielding art of Aikido to students who are trying to learn the resisting art of Taekwondo).
Most martial arts use one-step two-step, three-step, etc. sparring and self-defense sequences as a part of their curriculum. It is an easy way to teach a large group of students safely, it helps, students learn to interact physically with other students, and it is an easily graded standard to use during rank promotion testings. Each organization, and sometimes reach school and instructor has its own step sequences that it uses. You will have to find a book, web site, or video that specializes in your particular step sequences.
I am of the school of thought that that believes that teaching specific reactions to specific actions is counterproductive. In a step sequence, you learn to do “this” in response to “that.” If “that” does not occur or “this” does not work, then you are bewildered. If you use knife defense # 3 and you miss grabbing the attacker’s arm, now what do you do. People do not have the time learn and become proficient at specific responses to every type of attack.