Believe me, this is not a player to whom one can say something like this and have it stick.
Why not? I mean, I get not wanting to have arguments over what is or is not canon during a game, but why does this guy cling so strongly to a video game?
Which is fine in the fiction, but to replicate that at the table I-as-player need a map so I can plan my approach and getaway routes, determine distances and-or expected travel times as best as possible, know where obvious fixed-site threats (e.g. the cop shop) are located in order to avoid them, stuff like that.
And I wouldn't want to just handwave this by the GM saying "your character knows all this", as for me it'd be far more fun digging in and having us work it out for ourselves...literally role-playing the gang sitting in a basement around a map plotting out these details for the score.
And if we really wanted to get creative, we could even try to locate our scores to form some sort of pattern on the map.
There is a map of the city, but it only details some major areas. There are maps you can find online that have much more specific detail (down to naming each street and canal and many of the buildings), but the game intentionally leaves these kinds of details up to the group.
So when the need arises for a specific location, the GM can pick a spot for it, and there it is. There’s no reason they can’t also label the map so that that location is set.
This is what I’m talking about when it comes to prep. There’s no need, nor really any benefit other than preference, to determining all these locations so specifically ahead of time. Not when you can absolutely do that in play if that level of detail is needed.
Which would most likely mean retconning that whole encounter and at the very least would invalidate all play that came after. As a player I'd be furious; as a GM I'd be embarrassed as all hell (and I speak from experience on both sides here).
It’s hard to engage this half-sketched example. Why would you allow an error on the GM’s part to stand in such a way? Just amend the detail in play and don’t have the PC die because of the mistake. Why go through it all and then retcon it afterward? Just pause, acknowledge the situation, and say something like “Okay, so you had decided to make a run for it expecting the wall to be much shorter because that’s how I described it. My bad. We’ll go with the shorter distance, and you make it around the corner before the arrows hit. Sorry about that.”
Seriously, I feel like you’re inventing concerns that simply aren’t much of an issue, nor are they any more prevalent than they would be in prepped play.
As a counter point, I’ll bring up running Tomb of Annihilation in my 5E campaign again. Running prepped material was far more prone to errors....room sizes and positioning and all that kind of stuff matter much more in a traditional dungeoncrawl. I made a lot of minor descriptive errors, either because the room descriptions were tricky or (more often) taking what was in the book and translating it to players just allowed for minor errors or omissions.
In this sense, I can see how you feel that details of this kind are a requirement...it’s all potentially relevant when the trap goes off and so on.
But it’s not necessary if you’re not playing in a manner that requires it. If the system or the playstyle isn't really worried about the exact location of each PC when the trap goes off....if there’s another way to handle it than D&D style grid maps and area of effects....then you don’t need that stuff.
There were far less errors once I realized the issues we were having with Tomb of Annihilation, and I adjusted. Once I wasn’t as concerned with adhering to the prepped material, our play became much more smooth and enjoyable. It was likely more cinematic and less simulationist than what you’re proposing, but there were far fewer errors of the kind you’re concerned about.
I mean, look at the example of the 800 or 600 foot wall. The conflict comes from you having one written down and then saying the other to the players. If you don't have one written down ahead of time, there’s no conflict....the “truth” is simply what you’ve told the players.