- The concept has to be one worth returning to. Older gag-a-day strips have their stock characters -- overbearing mother-in-laws, clumsy protagonists, dim-witted sidekicks -- who provide the source of these themes. But many of these characters are as outdated and stale as Borscht Belt stand-up routine.
- The concept has to be reinterpreted in substantially different ways. Garfield gobbles down a pan of lasagna in a single gulp. Garfield gobbles down a cake in a single gulp. Garfield gobbles down [a comically large portion of food or drink] in a single gulp. Sure, it's riffing on a theme, but the humor quickly wears thin. Whatever food is depicted in the first panel will be gone in the last. Ha ha.
Lio's creator Mark Tatulli scores high (in my opinion) in meeting both these challenges (Lio and the Fourth Wall). As in today's example. The concept: make the comic strip's borders part of the strip itself. The interpretation: well, that depends. Sometimes the border is a wall to be broken through. Sometimes it's a rope to be cut, sometimes it's two-dimensional, other times it's three-dimensional.
This sequence from 3/2/13 is but one example of how Tatulli plays with convention.
(click on image to enlarge)