Perfect tenses for talking about the past experiences

[Natalia]

I’ve learnt from an English grammar book that when we are talking about something that occupied a period of time now terminated (especially with the verbs “live” and “work”), we should use the past simple. Here are the examples:
- He worked in that bank for four years. (but he does not work there now)
- He has worked in that bank for four years. (he still works there)

Having said that, recently I watched some English videos in which native English speakers talked about their past experiences and used the structures like:

- I’ve lived in Vietnam.
- I’ve worked in the accounting field for 4 years.

So I thought maybe we could use the perfect tenses to highlight the present relevance of a particular past event? For example: I’ve lived in Vietnam = I have some valuable experience of having lived in Vietnam. That’s how I understand it but can be wrong of course, and that’s why I’d be very grateful for your feedback on this.

[Daniel]

I’ve learnt from an English grammar book...

That's the problem. You're going to get over-generalizations meant for learning the most common patterns, but they're often not actually accurate descriptions, and certainly do not cover all usage.

In this case, the issue is present relevance: is it currently relevant that you have experienced living somewhere? If not, if you're just describing the past, use the past. If you're stating something about your experience (for example, a friend is thinking about moving to that same place) then you'll use the present perfect. You can think of a paraphrase as "I have the experience of [verb]".

[Natalia]

OK, thank you. I thought that the issue was present relevance. But just to be sure, let me ask you two more questions:

1. Is it fine to add how long I have lived or worked somewhere in the past (as in the example "I’ve worked in the accounting field for 4 years")?

2. Since the present perfect progressive is used to talk about an action of certain duration which may also have a result in the present, can I also use it in the same way as the present perfect simple above? (i.e. to talk about a past event which, to me, has some present relevance). For example, look at the response to A which I came up with and tell me please if it makes sense.

A: Have you travelled a lot in your life?
B: Yeah, I've been living in different places. For example, I've been living in Spain for 3 years.

[Daniel]

Yes, if relevant.

[Natalia]

And what if you are at a job interview and your potential boss asks you to tell them something about your experience, about your previous jobs. Which form would be better to use?
1. I've worked in accounting for 4 years
2. I worked in accounting for 4 years.

On the Internet, I've found this model: I've worked in "occupation" field for "unit of time".

[Daniel]

Yes, that's relevant. (1) refers to experience leading up to the current moment, and (2) refers to something you did in the past but maybe not relevant now.

[Audiendus]

2. Since the present perfect progressive is used to talk about an action of certain duration which may also have a result in the present, can I also use it in the same way as the present perfect simple above? (i.e. to talk about a past event which, to me, has some present relevance). For example, look at the response to A which I came up with and tell me please if it makes sense.

A: Have you travelled a lot in your life?
B: Yeah, I've been living in different places. For example, I've been living in Spain for 3 years.

I would not use the progressive form here, as that implies that you have only just returned from Spain  (and that you lived in various other places consecutively before that). If your stay in Spain ended some time in the past (but is relevant to the present), you can use the present perfect simple:

B: Yeah, I've lived in different places. For example, I've lived [or I lived] in Spain for 3 years.

With the present perfect simple, it is usually clear from the context whether we are referring to (a) something continuing up to the present, or (b) something that ended in the past, but is relevant to the present. The following well-known joke by Groucho Marx plays on those two uses of the present perfect:

"I've had a perfectly wonderful evening, but this wasn't it."