OK - I've been chewing on this issue and I think I've ferreted out what the source of the disconnect is.
The MC Rules are RULES
So - you're not bound to some kind of simulation where "all of the PCs are thinking about the situation." You're bound to the rules, which say that you're having a conversation.
In that conversation, you're hearing one player at a time. Because everyone talking over each other ceases to be a conversation and the game doesn't operate on a shouting match. So someone has to read the sitch first.
Now, this doesn't reduce the whole question to whoever's quickest on the draw, it doesn't mean that they who hesitates is lost, because, remember, we're having a conversation.
So let's say your party is going to meet an ambitious operator, Macy, at a joint in the hardhold. At some point, in response to "what do you do?" someone has said, "Well, I'm scoping out the joint, trying to get a read on Macy's intentions. Is this just a sit-down or is something else happening here?" The conversation isn't just, you know, over. If someone else says, "Hey, yeah, that's what I was going to do!" and especially if you get a chorus of similar responses, you've now got to work out (as a table) who's reading the sitch right now, who's helping out (and you know...how), what exactly "scoping out the joint" looks like, etc. and you'll end up with one and only one move being chosen.
First of all - that's what the MC Rules say you do. When a move is triggered, it is your job to resolve it, that's the rule. It's not a guideline. It's not about simulating reality, where things happen simultaneously, it's about responding to an event in the conversation - even though there may have been some back and forth about it, some clarification while everyone got into the same fictional space.
Second - one of the key things about AW and PbtA is that no roll ever boils down to "nothing happens." Something is going to happen as a result of this move and because of that, every other "read a sitch", had you tried somehow to wrangle them all simultaneously, would be immediately invalidated - because the sitch they'd read would no longer exist, having been altered, irrevocably, by the outcome of the first move. Where this really shows itself is on a miss, of course, where you, again, are required to make a move, but because moves snowball, and the fact that no roll ever resolves to "nothing happens", once again, the situation should be sufficiently in flux to make the extraneous reads irrelevant.
Play should continue and if really, genuinely, the sitch stays charged long enough for someone else to read it, I'd go ahead and resolve that one - but there's a good chance that the +1 for acting on the information from the first one is gone now, because, you see, that sitch is also going to change as a result of the new roll.
But really - there is a limited number of things that can happen after the sitch gets read:
- The PC who read the sitch gets a miss - now you have to make a move that will change the sitch
- The PC who read the sitch gets a hit and makes a move based (presumably but not necessarily) on what they learned - that'll change the sitch
- Nobody does anything concrete (reading the sitch isn't concrete) in which case they are looking to you to find out what happens and then you have to make a move - that will change the sitch
Addressing specific issues from comments
The crew is eating in their hardhold, when they hear the buzzing of the Highway Clan in the distance. Jomes reads a sitch...
How? What does that look like? What does Jomes do even? And, I'm going to ask this a lot - how is this a charged situation? Where's the tension here? Where is the dynamic? "you hear a thing" is not a charged situation. "Jomes, you're standing atop the wall next to the gate while Uncle tries to get Bacon to turn the Highway Clan around. They're gunning their engines but no guns are out yet." - that's charged, something is on a knife edge, something is going to happen now. Hearing the Highway Clan sounds like a charged situation is coming up like you've advertised future badness but it's not here yet.
how should we figure out, as a table, who is reading the sitch "right now", when Stitch and Lucy both just want to think about the oncoming attack from the highway clan?
I suggest you do it like grown ups. "Thinking about" isn't the same as "thinking something through". The one is basically instantaneous (and frankly, I don't think should trigger the move, because then everyone is doing it all the time which is your exact problem) and one takes considerable time and someone's attention, it's deep consideration. Figure out who's putting something at stake here and come to an agreement. If both are putting something at stake, let the table decide who's stake is more interesting.
the entire squad is going through a warehouse together and all of them are looking around and keeping a look out...
Again - what's charged about this sitch? How does walking through this warehouse mean that something is going to happen? I'm getting the sense that you think "read a sitch" is the "perception roll" of Apocalypse World and it just plain isn't.
I think I've addressed the rest of the comments so I'm going to leave this for now.
You don't try to resolve simultaneous actions because there's no such thing as simultaneity. That's a rule too.