talking about general things - choice of tense to "set the scene"

Question

This is a question that I've been struggling with for quite a long time. I have asked a similar question in the ELL forum already but I didn't get an answer there and it is difficult to find information about my issue because there is no term to describe this topic (or at least, I am not aware of one). That is the reason why I would like to try it in this forum again.

Many sources describe the usage of the different terms in the English language and I can use them in standard cases but I don't know which term I have to choose / I can choose when I want to speak about general truths and I want to set the scene for the general part. Normally, all the grammar books say that we should use the simple present for general truths and facts, but I have heard and read many sentences where native speakers used both simple present and another tense together.

Some examples to make it clear what I mean by "set the scene":

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• I drive fast when I drive alone.
• I drive fast when I am driving alone.

Here "I drive fast" is the general fact (I always drive fast when I am alone in my car) and "when I drive alone" / "when I am driving alone" is a clause to describe the circumstance when I drive fast (I don't drive fast all the time but only when I am alone in my car). Which tense should I use in the second clause? simple present or present continuous?

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• It depends on the person who is judging.
• It depends on the person who judges.

Please, compare my question in the ELL forum: https://ell.stackexchange.com/questions/316338/general-statement-present-continuous-in-relative-clause

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• When someone sneezes, what do you say?
• When someone has just sneezed, what do you say?

Here, "what do you say?" is a question about something that you say each time in response to someone else's sneezing. Therefore, the simple present is correct. But what is with the when-clause, which is setting the scene in this case? In my mother tongue (German) both ways are acceptable. The reason why I would like to know whether or not I can use the second one is that in some situations I would like to give the events an order (First event: Someone is sneezing. Second event: I'm responding with "Bless you!"). Compare the following example (First event: The person is being shot. Second event: Metal pieces are causing pain.):

• When a person has been (or was ??) shot and hasn't got a proper surgery, some metal pieces can remain in their body and can cause pain even many years later.
• When a person is shot and doesn't get a proper surgery some metal pieces can remain in their body and can cause pain even many years later.

The same here: In German, both ways are acceptable

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A nurse is being told her tasks in the morning:

• Normally, patients get their medicine at night but it is possible that the nurses that were working at night didn't have enough time. In that case, you have to bring the medicine to them.
• Normally, patients get their medicine at night but it is possible that the nurses that work at night don't have enough time. In that case, you have to bring the medicine to them.

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A sentence that I have read in a museum:

• In any emigrant's journey, there is a turning point when they have left their home but not yet arrived. At this moment - a new life is beginning.

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I would highly appreciate thoughts about the questions:

1. How flexible can we use tenses in cases like in the examples above? If both ways are acceptable: Which one would you prefer in formal/informal speaking/writing?
2. Is there any difference in meaning between the example in simple present and the example with mixed tenses?
3. Can you think of an underlying rule or logic? (I really need logic to learn it)

Answer 1

In each pair of sentences, the two variants are roughly equivalent, and both are possible. But I think that sentences of the form "I drive fast when I drive alone" sounds more like a law of physics than a casual observation. Now some specific comments.

The judging example: I would say, "It depends on the person who is doing the judging." Sorry to be adding another complication! The other two options sound too abrupt to my ear. The thing about judges is that you can't control which judge hears your case, and judges vary a lot, from one to the other, so I guess I'm more comfortable talking about who's doing the judging in an even more immediate way.

Sneezing: the version without the progressive tense sounds like a rule of etiquette. There is a children's book, "What Do You Say, Dear?" that quizzes children in a fun way about basic etiquette, and illustrates my point.

Shooting injury: I would use the present perfect, "has been shot," but it's not wrong to use the simple present. To me, jumping from simple present to years in the future feels more abrupt than the softer present perfect.

Nurses: I would just say "the night nurse." Without that, the sentence feels too complicated. But I can't find any subtle difference between the two versions in this case.

I didn't understand what you're asking about the emigrant sentence.

Compared to my spouse (also German), you're doing great. My spouse gets horribly confused between present and present continuous, etc.