There are several confounding factors so it’s hard to know for sure, but I do think that Toastmasters has helped me improve at a specific sort of social interaction: having to talk when I don’t know a lot about a particular topic or when my thoughts aren’t well prepared. I’ve gotten a lot of practice at this with an exercise Toastmasters calls “Table Topics”. During Table Topics, each person goes up to the front, is given a prompt, and then gives a 1-2 minute impromptu speech on the given topic. Table topics force you to talk for at least one minute about ...
For example, if you have a "shy person" identity, then going to parties or starting conversations with strangers can generate counterexamples for that identity, and help to displace it with a new one of "sociable person". Costly signaling can be used to achieve this - for example, joining a public speaking club.
Counterintuitively, I think that joining Toastmasters has actually made me identify more strongly as an introvert, mostly because my introversion is never more painfully obvious than when I'm there. So, observing myself attend...
I've had success in similar situations by reframing things and adopting the "extrovert in training" identity. Struggling at the limit of my ability reinforced that identity, even when that limit was low. For example, an extrovert wouldn't attend the first 45 minutes of a party and then get overwhelmed and leave, but an extrovert in training would. Meanwhile, the identity reinforced my desire to struggle at the limit of my ability (maybe I can stay for 75 minutes), which led to rapid improvement. The general heuristic of reframing from "I am ...
That is a useful reframing. I’ll give it a try!