Is it necessary for RPG scenarios and adventures to have a pre-established structure? And more importantly, how does having a structure help a GM both read and run a game?,
Scenarios with a compartmentalised structure are - in my opinion - much easier to read, assess, compare and then run. When looking for a scenario to run a short notice, my preference is to skim through the pages – looking for what seem like great scenes, then backtracking to check that the detail of how the scenes link seems to be coherent and workable for my players. Then I skip to the end and check the finale, to see if it seems suitably memorable and pitched appropriately. Passing those tests, I then read the scenario and make notes about how I’ll run it. When the text runs together this assessment is much harder, and I need to make many more notes in order to run the game.
When I created EPOCH I set a set structure for scenarios - this was a layout that I felt had a dual purpose, both to provide a coherent story, while providing a clear vision for how the game would unfold, and to be usable when facilitating the game - allowing GMs to access information with ease. This structure was based entirely on my own preferences, although I assumed the utility would be apparent to all.
I was wrong. When I worked with other authors, I found that few of them submitted scenarios in any form that resembled the structure I had established for EPOCH scenarios. Indeed most were in sharp contrast the rigorous divisions I had established.
But what about other games? Here are some examples from scenario collections, selected at random from my bookshelf.
Example 1: Call of Cthulhu (Terrors From Beyond)
In the past I have found scenarios for Call of Cthulhu to be a leading benchmark of quality in scenario structure. They (almost uniformly) follow a similar structure, setting out a Keeper Background (which usually serves as a background and synopsis) followed by a section on 'Involving the Investigators' or 'Investigator background' which establishes the role of the characters in the scenario. Statistics for NPCs and monsters are usually found in the back (although sometimes on the body of the text as well). This is pretty good, but the coherence and layout of the main body of each scenario can vary greatly.
Example 2: Trail of Cthulhu (Out of Space)
Expands a little on the traditional CoC format by including sections titled 'Hook' (how the characters are involved) 'The Awful/Horrible Truth' basically the same as a Keeper background section, then 'The Spine' (a paragraph by paragraph summary of the scenario scenes) then some variance between scenarios but generally a section titled 'Scenes' which contains the bulk of the scenario. I think the addition of 'The Spine' is a significant improvement on the CoC formula.
Example 3: The Laundry (Black Bag Jobs)
No real coherent uniformity beyond a 'Mission overview' section which is usually a page or two into the scenario text, following a discussion of background elements. Player handouts are at the end of each scenario. Thankfully most of the paragraphs are small and easy to digest.
Example 4: Rogue Trader (Edge of the Abyss)
No coherent uniformity beyond an appendix containing adversary statistics at the end of the book. Ironically scenario two in the collection systematically establishes the setting, objectives and rewards for a series of encounters the characters can have providing a small oasis of order (and I found this was one of the easiest sections to facilitate when I actually ran this game).
Example 5: Paranoia XP (Crash Priority)
No coherent uniformity although most scenarios have a 'Mission overview' section somewhere close to the beginning.
My conclusion: few RPGs I examined imposed a systematic and consistent structure on scenarios written for their games. I think this makes it more difficult for GMs to rapidly assess information and use it in gameplay, and increases the variance of the experience for players. The ability of the GM to remember, prepare or bookmark key sections becomes much more significant and it is more likely that key details of the scenario are omitted, or changed on the fly by the GM.