Having laid the groundwork with the previous few posts, starting here, I'm in a position to discuss a relationship between blocking and RPG adventure writing, that struck me as I was reading this comment from Tim.
We're told to think in terms of the 'story' of the adventure ~ but as I've explained, this is a lazy use of the word from game makers who did not have the vocabulary or the design-experience necessary to find the right word in their lexicon. A proposed adventure is a delivery system for communicating a set of ideas to the players which will produce a vaguely understood but ultimately unknown behaviour, the same way that a phone app will be designed for one purpose and then find itself being used very differently once in the hands of the public.
The correct term for this design process is "modelling," which the reader will note is the term used by experts when discussing the principles of design, such as here, here, here and here. If we take the last, which is about security systems and threat models, the professor ~ after some introduction ~ talks about how the security system is based on achieving a goal when there is an adversary present: and this is more or less the principle behind what we should be thinking when we are designing a dungeon.
The type of dungeon being entered should be based not on the environment or the amount of treasure or how dangerous it is, though these things matter and are ultimately part of the system, but specifically how rigorous is the dungeon in terms of dealing with the players as invaders of that system. Is the dungeon open or closed? Prepared or not prepared? Do the denizens of the dungeon expect a threat or has the likelihood of a threat become minimal to the point where the denizens have become quite lax. Specifically, how much confrontation should the players expect once they've entered the model?
Most of the original dungeons that were created by the early adventure designers were built like a series of museum exhibits, each with something different and interesting to show but no real continuity from location to location. There have been varying attempts to move away from this model but it continues to turn up again and again in dungeons made by DMs who just don't know any better and who can find plenty of examples to support the notion that this is good design. In fact, the dungeon should be organized in a manner that suggests that the denizens within are as free to move from room to room as the players are. If the rooms are separated by fixed, nearly impassable walls, then the dungeon rooms so divided can exhibit a severe break in continuity; but if the players can just walk through a door or move down a passageway into the next room, then it should be assumed that the monsters can also: and if they can, why are the rooms arranged in the way that they are?
This is where we might imagine that we need 'blocking' to determine the arrangement of the rooms or the denizens within; but blocking is an inflexible structure for the movement of theatrical characters moving according to the rhythm and time-sense of the lines of the play as it is presented, or the inflexible plot points of a piece of literature that is meant to be experienced but which does not allow interaction. The monsters within the rooms the party is investigating will move according to the players' behaviour, or their lack of behaviour.
Consider: as a DM, you stipulate that the snake in the fountain will be moving slowly through the water at the moment the players enter the room. We can think of that as blocking, if we want; however, what the party does can change the habits of the snake, even if the party does not know the snake exists. Suppose than none of the players approaches the fountain? Suppose that one player decides to remain as a guard in the room, while the rest of the players move on to the next room? What then? Does the snake leave the fountain or not? We know the snake finds food by passing through the cracks in the wall. At what point does the snake leave the fountain to do so, enabling the player to safely watch the snake cross the floor while remaining unthreatened?
The tendency is to always assume that the snake is a threat: that if the party will not go to the snake, the snake will go to the party. But we may easily play an entire golf course and never hit a water hazard; does that mean that the water hazard should come to us? Or that something is wrong with the golf course? Nonsense. As a designer, we have to see the design features of the model we're creating as flexible enough that the players can avoid hazards. And we have to see those hazards as living, breathing things, that won't remain in a static position within the system, just as the players are not in a static position.
Too often, we have tried to account for dungeons as a series of demanded expectations: the thought process has been, when the players do this, this happens. We should be thinking in terms of "if," and we should be thinking even better in terms of not having a certain response on the part of the monsters being fixed and inflexible.
If the monsters are vigilant, if they are certain that their lair is being invaded and they do feel reason to be threatened, they should fight like a cornered animal, perhaps to the last creature. But if the party has reached the dungeon through a trackless waste, only to finally find these creatures within, how vigilant should we expect them to be? Would they not, perhaps, be interested in news from the outside world? Might they not first seek to parley, then fail to understand for a time why the party is so violent and obsessively murderous? Could this not send a ripple down through a dungeon, where different groups have created negotiated boundaries between various lairs, which are now communicating as the word is sent down through the sixteen layers that the orcs on level 1 and the bugbears on level 3 have been nearly wiped out, except for a few left over who are now speaking with the ogres on level 6 or the hill giants on level 7?
Dungeons are virtually always seen as collections of targets; as museum exhibits; where the monsters stand frozen in time until activated by the players' entrance. But the player's decisions, speed of movement, order of investigation, access of magical power within the space and so on should influence what position the monster is in when the players arrive, how much intel the monster has had the opportunity to gather, what other forces already know about the players and what disturbances have occurred. These things make running a dungeon vastly more complex ~ but ultimately more interesting for the user.
Remember that line from Salen and Zimmerman: play is free movement within a more rigid structure. More rigid. Not totally rigid. Your personal control in driving your car is more or less predictable; but that predictability changes if it rains or snows and changes the surface of the road, and changes again if you wait three hours before getting on the highway to visit the nearby beach or campground where you hope to sleep tonight. Waiting can produce a better effect and it can produce a worse effect. You might wait and avoid the rain. You might wait and find the campground is full. You might wait and discover that you're so hungry before you reach your destination that you must now make an unscheduled stop. Your decisions have consequences to the way the complex, multi-varied world operates, both internally to the structure of your biology and externally to the structure of what nature and everything else is doing while you make a decision to act.
Whenever possible, a DM should try to stretch far enough to account for those decisions, giving enough free movement to the player to let them play, while enabling the structure to shift and adjust in response to that play. The car works in a rigid way; but the wheel still turns. The world the players participate in has to turn as well.