You misinterpret CAN for ALWAYS. If the INFJ is just plain stupid than they aren't going to make intuitive claims about what the ISFJ is droning on about, and will have to listen closely to understand what's being said. What you're talking about is every INFJ knows the headspace of every other type, all the time, which is not what I've suggested at all. All I'm suggesting is that INFJ's have a weakness with the ISFJ because we naturally make rational mental leaps in our minds that ISFJ's don't necessarily make so quickly about what someone is saying. The mental leap is usually internal, thought out, and confirmed or denied well into the ISFJ's talk. If the INFJ is smart and listening, and knows where this ISFJ talk is going and they are bored, they will interject and start finishing thoughts, which like I said, can lead an ISFJ to become surprised by the mental leap saying "how did you know what I was thinking?" or like you guys keep saying lead the ISFJ to say "Stop interrupting me, that's not what I mean" If the INFJ is really interested, they will hear the ISFJ out and listen to confirm or deny what they're already thinking. It's a matter of, is it worth it, to listen to what I already know and have already figured out in my head? The weakness is a feeling of boredom almost on the INFJ's part, and it's specific to the ISFJ. Again, it's a matter of personality and mood between the two during the conversation as well, what headspace everyone is in.
Your experience is totally different from mine in how you read people. Generally after a few brief moments with someone I know which way the wind is blowing, and have a general sense of what the other person is all about. I don't know what people are like before they start talking, but after a short while with them I've made several rationally intuitive claims about them, that are more true in the end, than when I first met them. As well, other sides are revealed.
I have this ENTP Type A girl in my life and she's totally "bull by the horns", leader, go go go go go, all the time, and I enjoy talking with her, but I wouldn't want to date her. Her idea of having fun on a regular basis is a full schedule from the moment she wakes up until the moment she falls asleep, with marathons in between. Done as though it's all like having a cup of coffee. Bizarre to me. I like asking her things she doesn't like to hear, just to see how the conversation will go. Things like taking time to relax and meditate and making time for repose to gather your thoughts. How people are not all the same and people are different and are in perfect liberty to choose what it is that they deem relaxing and enjoyable, and that they don't need to be the same as you, to be doing the right things in life. It seems funny putting that down in writing, but it's nonetheless true, lol. All people should want that, is the message she puts out, and I'm always playing devils advocate, describing how that doesn't lead to the maximum benefit for everyone. She has confessed that she needs to work on that, and does recognize that it's not right to implant her own way to live on everyone, although, I find it funny how strongly she feels about it really being so in life. Any thoughts?