I use socionics mostly as a categorization tool. I didn't learn anything about myself since how I thought about things prior to knowing about socionics is the same as how I think about things now. It's just that I can now associate how I think about things with the label of ILI (or maybe LII). I guess typing yourself properly requires introspection and so the process of using socionics made me learn stuff about myself, but I think it'd be a stretch to say that I learned more about my own cognition from the profiles. Rather, I looked towards the profiles to see if I actually do the things they say that that type does. Anything else would be mere bias and, perhaps, influence by the forer effect, if you wanted a particular outcome.

Socionics is a system of correlations that is useful for predicting interpersonal relations. If you can type people based on means that are not IR, then you can reasonably predict how they'll affect one another. It's a powerful tool. Honestly, I'm not yet at the level where I can confidently type others very quickly, and so I rely on my own experience and intuition for interpersonal affairs more than I do socionics. However, I see how socionics can be a great aid in this process, which is partially why I study it.