On the difference bewteen present perfect simple and continuous

Question

I've done a quiz here to check my understanding of the difference between the present perfect simple and continuous. I made two mistakes and I don't understand why I'm wrong.

---

What I answered:

Q5: I have drunk more water recently, and I feel better.

Q12: Iona is exhausted these days. She has worked too hard recently.

The correction given:

Q5: I have been drinking more water recently, and I feel better.

Q12: Iona is exhausted these days. She has been working too hard recently.

---

I'm far from being a beginner in English and I have to admit that I answered the quiz without thinking it over that much as it sounded good to me.

However, I checked the grammar book I used to use "Cambridge, English Grammar in Use, Raymond Murphy" and he says in unit 8 and 10 that we use the present perfect when using "recently" and I would say it makes sense to me as "recently" refers (to me) as something already done and so we are speaking about a consequence, in those cases, "I feel better" is the consequence of "I have drunk more water recently" and "Iona is exhausted" is the consequence of "she has worked too hard recently".

In the grammar book, he also adds in unit 10 that when speaking about the result of an action one should use the present perfect simple.

I would be glad to understand why I'm wrong, thank you in advance.

Answer 1

There is very little difference between these tenses.

Using the continues can suggest a repeated action, so it may be more natural for the idea of "drinking water" in which the action of drinking must have been repeated.

Similarly Iona has worked hard on multiple days. It's a repeated action so a continuous tense is appropriate.

However the present perfect is grammatically correct and the meaning is so similar that I would not be surprised if a native speaker used present perfect in those situations. Nevertheless, for the reasons above, the continuous form is better.