So I appreciate the detailed reply. I think in a lot of ways we agree, and I think that mostly it's just a matter of preference in how we approach gaming. I'm gonna snip it down a bit, because I feel we're drifting away from matters related to agency, and I know we've talked about a lot of this stuff before in one way or another.
Fair enough...these do get rather unwieldy.
There are times where it can be interesting to watch the players pause and then debate what to do about a situation, how to proceed. But I like when those moments are reserved for kind of major moments. When the decision is not a major one, I want things to move. I don't like those big pauses happening often.
This can be a product of the system, or parts of it. It can be for other reasons, too, of course.
Thing is, as the PCs have no way of knowing whether what they're deciding on is major or trivial it's only fair the players don't either.
Depends on the specific players too. If you get two or three over-planners in the same game be prepared to spend a lot of time waiting for stuff to happen - or be willing to bring the heat: wandering monsters can be your friend.
Sure, that's all great. I agree about the group being the focus. But I prefer when each PC also has their own things going on, their own agenda to pursue. Focus can rotate as needed, and I would hope the players are all okay with indulging a little time spent on characters other than theirs now and again. Plus, the characters are usually invested in one another, so getting their help doesn't usually require a lot of convincing.
To some extent, I agree. But when half a session or more goes into one PC's family drama it gets a bit much.

(example: as a player right now one of my PCs is just coming in from the field and has some family stuff to see to before he heads out again - my hope is to resolve it with a few die rolls and the DM telling me how much I have to spend; so as not to bore everyone else with it).
I think this ties into a lot of the things that others are mentioning, where the players are able to shape the content of the fiction. It's about their characters.
Perhaps - but about their characters as a party or their characters as individuals, is the question.
So let me say this....if I'm in your game, and a volcano explodes when our PCs are near it, I'm not gonna buy that this was a neutral decision. Sure, you could show me some notes that say you had predetermined that this thing was gonna blow on August 5 of whatever year.....and then I'm going to point out how you're largely in control of the pace, and the date and of possibly dropping prompts into play to get us to go near the volcano.
I just as easily could have dropped hints trying to steer you away from it - but when do players listen to DM hints anyway?
And if the volcano erupts when the party is no where in the area....I'm very likely not to care at all.
If the whole goal of this is to set up some kind of legitimacy to the idea of neutrality, it just seems odd.
It's to also set up the idea that history is happening around the PCs above and beyond their own purviews.
So you have a GM plot you want them to engage with. It's fine. Where is the player agency in this scenario? Probably to decide to go after the book in the first place. Then, most everything else is "the world" responding to what the PCs are doing.
The agency this player has right now is immense, though she might not realize it: her PC has what everyone wants, and no matter what she does with it that action is going to change the fiction's course, probably in a big way.
But really, there is no "world" so it's the DM deciding what happens next. All the stuff about the necromancers and the foreign ones learning of the book (how did that happen? It seems it happened to further the plot, but I imagine it would be described as "the world responding to the PCs' actions) and then attacking the PCs and waging war on the town, and placing bounties on the PCs.....all of that is the GM having a story idea.
It's not bad. It just doesn't appear to have a high level of player agency. It's the GM constructing a story in advance around the PCs. Or at least, that's how it seems.
It's kind of a game-world response. I didn't pre-plan the idea of this Necromancer war in the slightest, but when the party ended up taking over half a year on what I-as-DM initially thought would be maybe a 2-month venture I started thinking about what the ramifications of that delay might be, then rolled some dice and came up with this.
Why would the GM ask more than one player to confirm what was to the North? Why would more than on player be attempting a check to determine the terrain?
Can't speak for anyone else, but for me if something's not described by the DM then my own imagination's probably going to fill it in. Thus if all the DM tells me is that we're in a swamp I'm going to start thinking in my own mind about what's around that swamp. As we haven't been told we can see any hills in the distance I have to assume there aren't any; so it's forest in one direction, open water in another, and more swamp in a third; and if I-as-player am asked what's out there that's what I'll say.
But when a player drops in that there's hills to the north (that we-as-PCs in theory can bloody well see!) a) my imagined scenario gets upended and b) the GM's powers of scene description get called into serious question.
I mean, if you put a river that flows north to south, how would it later become relevant that it has to flow south to north? And how would this river only be susceptible to this if it was placed at the time of play instead of months before?
Not sure if you're understanding what I'm not-very-clearly getting at, so let me try again.
If one person designs the setting ahead of time there's way more opportunity to find and iron out any inconsistencies. But if the setting's designed piecemeal at different times by committee as play goes along those inconsistencies could become a big headache. Example:
During some run of play in a city the flow-direction of the big river running through it becomes important - maybe someone wants to float down the river to escape something and someone needs to author what pre-established parts of town they'll pass through or end up in - and it's determined the river flows south-to-north.
During a different and unrelated run of play (maybe something to do with a swamp!) it's for some reason determined that there's hills to the north and mountains beyond that.
During a third unrelated run of play it's determined there's open ocean not far to the south - maybe someone was looking for a particular herb that only grows along the seashore.
Taken independently there's nothing wrong with any of these. But put 'em together and now you've got a river trying to flow uphill. And while you could easily say "Oh, just turn it around and make it flow north-to-south", that would retroactively invalidate the run of play that took place in the city which for me would be a game-wrecker.
Having just one hand on the helm doesn't eliminate the chance of this happening but does greatly reduce it.