Paul Levitz probably thought about what a comic book writer does more than any of his contemporaries, or mine, and during his dozen-plus-years stint as writer of The Legion of Super-Heroes, systematized what his predecessors did haphazardly, if at all. Then, as an aid to his own work, he created three versions of the Levitz Grid  Basically, the procedure is this: The writer has two, three, or even four plots going at once. The main plotâ€”call it Plot Aâ€”occupies most of the pages and the characters‘ energies. The secondary plotâ€”Plot Bâ€”functions as a subplot. Plot C and Plot D, if any, are given minimum space and attentionâ€”a few panels. As Plot A concludes, Plot B is „promoted“; it becomes Plot A, and Plot C becomes Plot B, and so forth. Thus, there is a constant upward plot progression; each plot develops in interest and complexity as the year’s issues appear.
Additionally check out The Levitz Paradigm: „The best imitation of life possible in a work of fiction“