Since this is the theory page, and since I can't sleep at the moment, perhaps I'll take a shot at defending the one-line tossup. Or at least I'll consider any possible advantages in a somewhat neutral manner, since the disadvantages have been addressed at length. [Note: when I refer to "short tossups" below, I'm referring to the dreaded one-sentence tossup with 1-2 clues, maybe 3 tops.]
So what hypothetical advantages might a set of one-line tossups have over a set of pyramidal tossups? A couple spring to mind. ...
 You can fit far more tossups into the same amount of time, assuming all other factors are equal. In reading a timed format with mostly one-sentence tossups (and 2- or 3-part bonuses) in Florida in years past, I'd hit anywhere from 40-60 tossups in 24 minutes, roughly the time it takes me to read a typical invitational mACF pack with 20 tossups.
, or perhaps [1a] You can ask about many more topics on tossups when twice as many tossups are read.
I don't think either of these comes close to outweighing the disadvantages, but there they are. And I suspect that to those who like short tossups, these are not inconsequential points. Just as I like to hear as many rounds as possible when I travel 7 hours to go to a tournament, those teams might want to hear as many questions as possible. (That's not relevant if the number of questions per round is fixed, of course.) I'll throw in a few other possible advantages which may or may not be valid or relevant.
 Short tossups may create a faster-paced game.
 In the specific case where an audience is involved (e.g. a TV show), shorter tossups may better fit the audience's expectations of a quizbowl competition (whatever that means), in addition to being more practical in the sense of the first 3 points. The audience is also more likely to hear almost the whole question with short tossups, whereas they don't get to hear a larger fraction of a pyramidal tossup.
 Shorter tossups are easier to write, especially for inexperienced writing staffs, and especially when a time crunch is involved. Of course, any time savings may be offset by having to write twice as many questions. (And in reference to my later babbling, writing a short-tossup set capable of differentiating amongst teams would involve some time in planning.)
 Short tossups are easier for an inexperienced moderator to read. Or they're harder to screw up, since there's less volume of verbiage, no between-sentence pauses, etc. Of course, more tossups may require more rapid back-and-forth from tossups to bonuses, which could hinder an inexperienced moderator.
 Hearing more questions (if relevant) can improve a more knowlegeable team's chance of winning. For instance, a 20-tossup round with 4 lit questions may have 2 questions on books which members of the much weaker team B had to read, earning team B a split. With questions on twice as many literature topics, team A's advantage increases.
One could also add the game-playing aspects of outracing the opponent on the buzzer, but I don't want to cause any arrhythmias among those reading this. All that said, I don't see either the advantages or the "advantages" of the one-line tossup outweighing the advantages of pyramidal structure.
So on a related note, is it possible to write a question set which uses one-sentence tossups but still meets the goal of effectively differentiating amongst teams? Can answer difficulty replace sequential clue difficulty as a means of separation? If some organization paid you to write a tournament set but insisted on one-sentence tossups, could you write a set which effectively differentiates amongst teams? I think it is theoretically possible. A well-written set of bonuses differentiates between teams of different levels, and bonus parts are essentially one-sentence clues. If (say) a bonus on the 1824 election can differentiate amongst teams by asking about Jackson, Clay, and Crawford, why can't a set of one-sentence tossups of similar difficulty accomplish the same goal?
To answer my own question, a fast-on-the-buzzer team with less knowledge might steal both Jackson and Clay, leaving only Crawford for the more knowledgeable team. And for teams of similar level, as we know, the difference in bonus conversion is pretty small. As such, it would be tough to write such a set. I don't know that one can write a set that can (1) differentiate strong teams from middle from weak, (2) be enjoyable and accessible for all levels, and (3) differentiate amongst strong (etc) teams. As for goal 2, pyramidal structure seems far superior on that count, since every team has a shot at nearly every tossup; with differentiation based on answer difficulty, many questions will go dead amongst weaker teams. Goals 1 and 3 are tough to merge. Maybe the ideal circumstance is a tournament where most teams are at about the same level, like a state championship tournament with a small field of regional winners.
I reckon that's probably enough babble for me. I don't know that I offered any useful information, and I don't find these points compelling enough for me to prefer short tossups to pyramidal ones. But some of these might be points to address if you're in the situation of trying to convince a qb organization to switch away from one-sentence tossups.
--Raj Dhuwalia, planning to trim garrulous wording later
"Keep it civil, please." -- Matt Weiner, 6/7/05