Why is the perfect used instead of past continuous in "Every time I've visited her...she has been working hard"?

Question

Every time I've visited her in the last month, she has been working hard.

This is a sentence from a grammar textbook. I don't understand why we use Present Perfect Continuous instead of Past Continuous here. Could somebody please explain this to me?

Answer 1

We tend to use the past simple for past events or actions which have no connection to the present, and the present perfect for actions which started in the past and are still happening now.

Using past simple:

Every time I visited her in the last month, she was working hard.

"Was" implies a past action.

In your original example using "has been" it sounds more like each past visit where she has been found to be working hard is evidence that she likely is still working hard.