From a strict grammatical point of view, the present perfect is always used for an ongoing situation that started in the past. The difference between the continuous and standard form is tenuous as they are basically stating the same thing, however the continuous appears to stress the ongoing action. I would introduce both at different time, then state that there is not much difference and later run a final drill to see that the students can switch at will, as they wish to use that nuance. It is not an important distinction as I understand that by now your students understand pretty that these are basically stating the same fact. Sometimes you have to check because students do not always let you on that they do not understand.
There are also regional variations of the usage so I would go with the flow. Because communication is swift you don’t want them to register as more different from the local population than they already are. So you have to be a bit formal. Unless you are teaching a horde of wanna be rappers. Then you must adapt.
However, languages are not hard core science. For example using “I have been exercising all morning” when it is now the afternoon. Sounds like a hard session. Also, in the long run usage, wins out, bending the rules. And quite fortunately so, or we would all be speaking Latin or whatever earlier language that evolved from something else.