I have just had a cup of coffee. This means that I'm not drinking coffee at the moment. But if someone asks me how I'm feeling, I might say that I've just had a coffee, because that's a description of my current state.
Now, I never smoke when I'm having a coffee. I hate the way that smoking makes my coffee taste - the coffee tastes disgusting. But after I've had a coffee, I always have a strong urge to have a cigarette. I don't want to have a cigarette when I'm smoking, but I always want to have a cigarette after I've had a coffee.
So I could phrase the situation above like this:
- When I have a coffee, I want to have a cigarette. (not good)
The problem here is that the sentence sounds like it's describing me wanting to have a cigarette while I'm drinking my coffee. I really want to describe the situation that I'm in when I've already had my coffee. I can use the present perfect to do this:
- When I have had a coffee, I always want to have a cigarette.
This sentence is better, because it says that when I am in an I've had a cigarette situation, I want to have a coffee. Notice that this sentence isn't about the past. It isn't about right now. It is referring to general time. It means I always want a cigarette in I've had a coffee situations.
Now consider the speaker in the Original Poster's example. They often have to give patients bad news. If you phone them up up one day and ask them how they are, they might say I have had to give a patient bad news. They're using the present perfect here because the giving bad news action is finished, but the phrase have had to give a patient bad news tells you something about their present situation.
Now this writer regularly has to give patients bad news. After he tells them the bad news, he often thinks a lot about whether he gave the news in a bad way. Maybe he worries about this for a few hours or maybe a few days. When he thinks about it, he never knows if he gave them the news in a good way or not.
The writer does not say that he thinks about it when he has to give them the news. He thinks about it afterwards when he is in an I've recently had to give someone bad news situation. To show this the writer uses a present perfect:
- When I've had to break bad news ...
This sentence isn't about the past, it's about every time that he is in a situation where he has just given someone bad news - now, in the past and in the future. What happens when he is thinking about whether he broke the news well or badly? He says:
... I never know whether I have done it well or not.
Here he uses the present simple to indicate it is always how he feels in this post-breaking bad news situation.
Conclusion
The anchor time, the time the author is speaking about, is the time after he has had to break the bad news. He doesn't use a present simple to describe this, because the breaking bad news always happens just before this time. He uses the present simple for the second clause because it describes the mental state he always has during this anchor time, the post-breaking bad news situation.
In my opinion, the writer could make the sentence clearer by changing a few words. They could use whenever instead of when. This would help us understand that this might be a recurring situation. Secondly, the writer could use the word recently or just. This would reinforce that the present perfect is to show the anteriority (earlier-ness) of the breaking news event:
Whenever I've just had to break bad news to someone, I never know whether I've done it well or not.
Notes:
Seeing the quote from this brain surgeon in a different context might help with understanding the situation. If you're a language teacher, teaching IELTS or TOEFL, for example, it's striking how much understanding context makes the sentence completely felicitous.
Dr. Henry Marsh writes beautifully about how difficult it can be to find the balance between optimism and realism. In one memorable passage, Dr. Marsh shows a house officer a scan of a highly malignant brain tumor and asks him what he would say to the patient. The trainee reflexively hides behind jargon, skirting around what he knew to be the truth: This tumor would kill her. Marsh presses him to admit that he’s lying, before lamenting at how hard it is to improve these critical communication skills: “When I have had to break bad news I never know whether I have done it well or not. The patients aren’t going to ring me up afterward and say, ‘Mr. Marsh, I really liked the way you told me that I was going to die,’ or ‘Mr. Marsh, you were crap.’ You can only hope that you haven’t made too much of a mess of it.”
One of the reasons why this sentence is easy to understand here is that we have a deep understanding of the importance of this problem for the future. The sentence does not - indeed cannot - be just a description of the past. It's a description of what the doctor has always experienced - but more importantly what the trainee and the doctor are both going to continue to experience every time that they have had to break this bad news. It's a situation that all such doctors will have to go through.
This is from a review of the book in ASC Surgery News