Ran my first session today. It was great! But I ran into this question a few times, where I asked someone to make, say, a City-wise test and two other players with City-wise would as if they could do that test too. Only the first player was asking about whether they knew this particular thing, but I didn’t know if there was any reason the others couldn’t also be wondering about that same thing. What’s everyone’s protocol for when multiple players leap to asking for a test? Should they be helping each other? Does that even make sense in knowledge tests?
If they did not genuinely declare intent and task, then they do not test.
In this case, they could describe how they’re helping with City-wise after you’ve called for the test. But “Can I test too?” should elicit a flat no in BW.
I think this particular example might have been bad, because as @luke points out with wises I should have probably been Saying Yes or not letting people help. But to take another:
There was a Perception test where the Intent was “find out if anyone nearby is listening in to our conversation”. The Task would have been “look around and see if anyone is watching.”
Now, every PC could do that, and that would be a valid intent and task for them all. So should they all get to do it?
I don’t think that’s what Luke was saying. You can Help with Wises, but, as normal, you gotta do something in the fiction to hand over the die; I like to ask my buddies for what they know about a topic, that way they can talk about it with me - Help. I’m also not sure Luke was saying that you should have Said Yes in this case.
Anyway, as to the Perception Test in question, what was the consequence of failure? Was there actually someone eavesdropping? If not, that doesn’t sound like a Test - “Sure, you look around. No one’s paying special attention to you. Roleplay in peace.” If someone is eavesdropping, “Ah, wise of you to check! Absolutely you’ve got a tail. Test Perception vs her B4 Inconspicuous! No, you all can’t also test; you shoulda been quicker on the uptake! This is the test to see of the tail is spotted. You can help, though!”
If the players are insistent they all have a legitimate intent rather than it being one intent with assistance, then remember that “too many cooks spoil the broth”. For example, three people individually checking for eavesdroppers are much more likely to look like they are being actively cautious and/or assume someone else is keeping an eye on a certain bit of the room than three people co-coordinating, so apply a Consequence of Failure that reflects it, such as if anyone fails someone’s noticed that they are being secretive.