I don't think that first comic would have made much sense without both girls and the narration, either.
Your latest two are quite good. Some advice: Give me brevity, or... would have been improved by the addition of extra rambling dialogue for Diablo in the third panel. Give us some visual reinforcement that he's rambling, don't just tell us. In fact, if you write the dialogue well enough, you won't need to use the narration to tell us time has passed; we'll know.
I like On Brevity a lot. My only problem with it is that the first two panels are both funnier than the last one, so it kind of ends on a weak note. I don't have any better ideas to suggest, I guess I'm just saying you have to watch out for that kind of thing.
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The what mentioned above is total fiction. Please don't take it seriously!