No. It depends. If she had been asked, for example, what she did at University, then she may have replied that she studied English at University (Because she has now finished her term at University. If the time referred to is indeterminate, then she would say she has (She said she had) studied English - it doesn't matter when, only that at some time she HAS studied.
Yes, that's what I wanted to ask.I understand you to be asking whether it is correct, in formal speech or writing, to use the simple past in situations where strict logic would call for the past perfect.
I'm so happy to hear that.I can't answer in terms of correctness, only in terms of likelihood.
I think you're more likely to hear the simple past used in conversation. I think you're less likely to see it in writing, especially formal writing.
I also suspect you're more likely to hear/see the simple past in AmE than in BrE.
But I understand panjaundrum's feeling. That's what I learned at school.s1 should never mean s2, but that's not to say that some people don't say s1 when they should say s2.
As I hope is clear from the above, s1 and s2 are different, they have different meaning.