I think the short answer is that there is some learning curve to using Zulip, but once that's done, sending messages like that takes essentially the same amount of time it would in another product.
The actual extra actions are:
* up to one extra keystroke to open the compose box
* typing a subject line like "projector C13"
You wouldn't have to search for a topic to send a message like that; you would just start a new topic. And "what's up w/ the projector in C13?? I have a meeting" would still be a perfectly fine Zulip message.
And then on the receiving end, you actually save a bunch of time.
* There's a simple keyboard shortcut ('n') to see the message that just came in.
* The fact that there's a subject line means that everyone sees "projector C13" and decides if they're a person that can respond to that, even if they aren't caught up on the rest of the channel.
* If someone does respond, you can see that they responded to your message, and not to some other conversation that's going on in the channel. That makes it easier to keep an eye on the conversation while the rest of you is improvising a solution.