Basically, the procedure is this: The writer has two, three, or even four plots going at once. The main plot — call it Plot A — occupies most of the pages and the characters' energies. The secondary plot — Plot B — functions as a subplot. Plot C and Plot D, if any, are given minimum space and attention — 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.This is what it looks like:
It's a grid. Rather plain, no? But from such unadorned schematics come fabulous narrative sleights-of-hand.
Most movies hew closely to this model -- the norm for Hollywood blockbusters is two, maybe three plots in flux. Consider how Mad Max (with its two conjoined plots) resonated more resoundingly with critics (and esteemed members of the Academy) than did Star Wars: TFA (which clearly boasts four, possibly five, developing plots -- or more). In contrast, television creators (like J.J. Abrams) have become increasingly sophisticated -- if not necessarily disciplined (again, J.J. Abrams) -- about the Levitz Grids they build.
The Levitz Paradigm is fairly common to genre novels, and nearly unavoidable in the geekier realms (Levitz' Wiki lists Tolkien and Zelazny as credited influences).
As for comics, fuhgeddaboudit. This is what Alan Moore's Levitz Grid looks like for a planned 12(!)-issue run called Big Numbers:
I'm under the impression that high-brow literary types mostly eschew something this rigorous, but that could be a slanderous misconception on my part (Ellis begins his observations on the matter by pointing out that James Joyce drew two charts that converge for Ulysses).
When it comes to reading novels, I'm more drawn to books with a single, dominant voice and its singular POV. This mode doesn't preclude a Levitz Grid, but multiple plotlines are by necessity channeled and filtered through a single consciousness. It's easier to read, in a way -- chalk the preference down to laziness, then.
Mind you, it could also be an unconscious recoiling from early and continuous exposure to the Bible, with its legion of voices and perspectives competing (often violently) to find a unifying theme. In which case, I say thank God for the likes of Miles and Frye, and their discerning eye on the Almighty's own Levitz Grid.