I'd admit that I do this moderately. I can get lost in my own head, but not so much with conversations. If I have something very important to say (like if I am meeting up with someone I haven't seen for a long time because my Fe sucks) and feel as though something NEEDS to be said, I practice in advance. Also, when I decide to call bullshit on close friends, I will practice outloud with my boyfriend or brother the various avenues to communicate it, the best wording, the possible angles to approach it, and how it will go from there. Do INFP's do this? Because what I'm describing here seems to have more to do with ENFP's manuevering conversations to go a certain way.. almost a manipulation. Hmmm. Kinda makes me feel bad
Generally I don't prepare, and do trust that everything that needs to be said will be said.
Man suffers only because he takes seriously what the gods made for fun - Watts
Intuitive thing to do maybe? Asking yourself "what if they say this or that?" results in these conversations, I haven't done it in a while as far as I can remember. I know an ISFJ who plans out entire conversations, you wouldn't even notice it because he weaves it seamlessly.
Oh, I don't plan out conversations that I'm going to have myself in the foreseeable future. That wouldn't do any good because I would probably get distracted and end up saying almost none of what I'd planned, so why bother?
What I do is I have conversations with people (sometimes real but mostly imaginary) or arrange conversations between two or more people (once again, mostly imaginary and occasionally real) in my head for funsies.
Well, it used to be for funsies, now it's mostly just mental chatter.