I'm INTP and I do this sometimes, but only if the other person is searching for the right words. I don't interrupt people. I want to be helpful and show I'm listening.
I also kind of hate it when people go on and on about things, but only if they're explaining something to me that I already understand. Then I'm like "yeah, yeah, yep, right, I understand, (and if it's my mother) I GET IT!"