I would just like to point out that in S3 when Sherlock’s been shot and then escapes from the hospital, John goes looking for him at Baker Street and sees that his chair has been put back, and straight up says “Why does Sherlock think I’ll be moving back to Baker Street?”
Not “Why has Sherlock put my chair back” or “What’s my chair doing back out here” or anything else, but “Why does Sherlock think I’ll be moving back to Bakers Street”
Someone else might ask those other questions, if they noticed the reappearance of the chair at all, or they might wonder why the chair’s back in its place all of a sudden but not be able to guess at why. But John works out what it means instantly.
John knows it was removed in the first place because sherlock missed him and didn’t want to stare at his empty chair, so that its back now means either that sherlock no longer misses him, OR that he no longer has a NEED to miss him, because John won’t be not there to miss. The only way that would be the case is if John moved back to 221B - hence, “Why does Sherlock think I’ll be moving back to Bakers Street?”
Anyone else would see that chair and either not register it at all, or not know what it meant that it was back there, but John works it out straight away.
John’s deducing, and he’s not even aware that he’s doing it