And yes, there is definitely a "leading up" period before we "go deep". There have been those handful of rare instances where I've been able to get really deep with another sx within minutes of getting to know them. It's like:
"Hey nice to meet you."
"So, I hear you work at X. Sounds interesting! Do you love it?
"Well, yes and no. I'm passionate about it, but I'd rather do it in a different setting."
"Passion! That's what I'm interested in. What is it that you are passionate about? Tell me more about that!"
"Um, OK, sure! How much time do you have?"
"As long as it takes. I wanna hear about it! I love that kind of stuff."
(Proceed to talk for 4 hours)
Those instances are super rare, but sometimes it happens where you can meet someone at a bus stop and just totally get to know what makes them tick. But, we know this isn't the norm - so we use small talk as a tool to "feel things out". If both people are sx, the floodgates will eventually come down. One of them will ask a good question or give a very in-depth answer, and it will just snowball.