conjunction "while" and the past continuous tense

[rou]

My daughter had some homework on the conjunction "while" and while trying to help her I found myself as puzzled if not more. You see, she had to complete sentences where "while" was used to link up a combination of past tense and/or past continuous tense clauses. What her teacher told her was that for a longer lasting action, she'd have to use past continuous tense (I understand this is not necessarily true but I think her teacher was trying to make things simple for them). Now, what her teacher didn't tell them was that when you have two long lasting actions going on at the same time in the past, and the same people are doing both, is this rule still good. For example, my daughter thought the following sentence was fine (and so did her teacher):

Peter was listening to music while he was studying.

I myself found this awkward and perferred something like this:

Peter listened to music while he was studying.

Where the people doing the actions are different, I'd think it's fine to have two past continous tenses clauses. E.g.

Peter was watering the flowers while Mary was walking her dog.

So, can any kind people enlighten us both?

[rou]

I checked my daughter's textbook and found sentences of the same structure. I still think they sound odd to me. I'd think if the same subject is involved in the two clauses linked by "while", at least the second time the subject should be omitted to make it smoother. E.g.

I'd prefer

I was eating popcorn while watching my favorite movie.

to

I was eating popcorn while I was watching my favorite movie.

So, any ideas anyone?

[rou]

Can any kind soul please give me some advice?

[2006]

Peter was listening to music while (he was) studying.

I myself found this awkward and perferred something like this:

Peter listened to music while (he was) studying.
Peter was listening to music while he studied.

Where the people doing the actions are different, I'd think it's fine to have two past continous tenses clauses. E.g.

Peter was watering the flowers while Mary was walking her dog.

Most people probably would use the same tense within a sentence, but you could not say that mixing tenses is (definitely) wrong. (even when you have different subjects)

2006

[2006]

I checked my daughter's textbook and found sentences of the same structure. I still think they sound odd to me. I'd think if the same subject is involved in the two clauses linked by "while", at least the second time the subject should be omitted to make it smoother. E.g.

I'd prefer

I was eating popcorn (while)(and) watching my favorite movie.

to

I was eating popcorn while I was watching my favorite movie. Most people would shorten this sentence, but it is not wrong as is.

So, any ideas anyone?

2006

[Tdol]

I'd prefer

I was eating popcorn while watching my favorite movie.

to

I was eating popcorn while I was watching my favorite movie.

There is no need to repeat the subject when they're so close, so as first version says exactly the same in fewer words, it does feel neater to me too.

Peter was listening to music while he was studying. vs. Peter listened to music while he was studying.

I think it depends on the context- the first might work better if explaining why Peter had failed to do well in a test.