Not just every time you talk on the internet, but every time you communicate in general. It becomes more intuitive over time, but it is something I always need to do. I often understand what I'm trying to describe better as a result of trying to translate it. There's satisfaction in challenging myself as well as finally being understood.
However, I sometimes start typing a comment only to give up on the original idea in favor of something short and easy. Sometimes I give up on the comment entirely if it seems like too much effort. Having to explain a second time is more work than trying to get it right the first time.
I rarely see info dumping as an option. If I don't care enough to put in effort, then it can't be that important in the first place.
If all else fails, I tell them that they aren't understanding me correctly, but make it clear that I don't feel like talking about it anymore. If a conversation isn't going anywhere, ending it is the best option.