While I commend the author for tackling a complex tense, I feel the focus is not so helpful.

Only at the end does the author focus on the most important aspect of this tense: the implicit current consequence.

In my experience living and teaching many years in four primary English-language countries, the listener needs to focus on the implicit current consequence of the past explicit action. The possibility that a Present Perfect activity continues into the future is nearly always irrelevant to the interaction.

The Present Perfect tense, whether Simple or Continuous, explicitly communicates about a past event but implicitly points to a current consequence. This is the essential point for the learner of this perspective. By using this tense we ask the listener to pay attention right now to guess a present consequence. Often the listener is not sure, which is why the listener often needs to follow up with a clarifying question, "What do you mean?".

Example: "I have been jogging" actually could mean "I am out of breath", "I am tired", "I am sweaty", "I am now fit" or many other possibilities.

So have fun with one of my favourite tenses in English!

In essence you must look at your current environment around you, intuit a past event (Present Perfect Simple) or past activity (Present Perfect Continuous) connected with your current environment, and then use Present Perfect to refer implicitly to the current consequence of a past event. It sounds complicated but I can make it very clear for your during an Italki lesson.

A great article, Gregory! Thank you so much! May I ask 2 questions?

1) In the last dialogue between John and Sally, is it possible to use Past Perfect Continuous in the sentence "you've been showering for a whole 45 minutes" (i.g. you HAD been showering)? If yes, would there be a difference?

2) Your example about the letter (just before the conclusion) seems so weird to me. I'd probably used Present Perfect Simple (the letter I've written) meaning, I've finished it. Would it be completely different? I just can't imagine a situation when I wrote a letter a long time ago, didn't send it and then out of blue decided to send it off with a previous call to the recipient :)

Thanks for your great job, Gregory! This is exactly what I need to feel nuances of Present Perfect Continuous: detailed explanations and examples with comments.

Tati,

Question One: No

Question Two: Yes I agree it's strange but it is possible. Imagine it's an important contract that has been delayed. Then you phone first to ensure the company expects the letter.

I hope that helps.

And I hope you enjoy the perspective of Present Perfect, because of the way it beautifully links the past with the present with a very clear effect on the listener.