Oh no, they are not! Do not make the mistake of thinking that repeat signs always coincide with bar lines, or imply them when they don't. None of the repeat signs in this piece coincide with bar lines, all four of them (halfway through the minuet, at the end of the minuet, halfway through the trio, and at the end of the trio) appear two thirds of the way through the complete and proper 3/4 bars which contain them.
I don't understand what you mean. Do you mean that the 2/4 bars are related to the 1/4 measure (like an extension)? I'm not saying it is wrong, and I have seen this before where measures do not add up to the time signature at the front of the piece. A pianist need only fill in the blanks in these cases (or leave out the blanks as it were)
Instead, he (mozart) set out to write a minuet, a format which already requires repeats, and so the decision to repeat wasn't really his own, it was implicit in the genre.
This is true, the minuet has a pretty ready-made form. I think most pieces use repetition in some way, like Johnathan said, it can be localized or large-scaled. When I took theory classes in college I studied from "elements of music" by ralph turek. I emailed him once and asked him how I could be a better composer. He wrote me a lot of useful information, one thing he said was he said he thought of composing as making one of three choices over and over again: to restate a musical idea, to vary that idea, or to create a new idea--Repeat, Vary, Create." and this is coming from a man who has analyzed hundreds
of pieces of music
I just cast my vote for "depends on the piece".
That's a safe answer!
I think it does depend on the piece. I think there are etudes that exist only to build a technical skill, but they won't have the same use of repetition that a minuet or a sonata would
(even though you might play them again and again to master the technique).
but don't composers sometimes ignore the 'rules' and do something different? I really don't know - just wondering about that. Like is it forbidden?
I think generally speaking (forget repetition), many composers ignore the 'rules.' A performance of John Cages 4'33'' (a silent piece) can and will not have the same impact as listening to a performance of a Mozart sonata
(though perhaps they are both pieces of "classical" music)
I think repetition is sometimes ignored by composers who want a through composed piece rather than a piece with form (which would probably have repetition). They say "constant repetition carries conviction" and so anything less than constant repetition still carries some conviction. I think that is what draws people to pieces with form more so than pieces that just cycle through new ideas without repeating any of them.
Little four or five bar sections that would repeat. That's okay.
I agree, long repeats are harder for me to grasp mentally. Anything over 8 measures is too much for me
isn't it up to the performer to decide whether or not to vary repeats, and what to emphasize?
It is the age old question, is it up to the performer on what to emphasize or is it up to the composer? There are some things that one cannot interpret, the notes, the tempo and whatever else is explicitly directed by the composer. No doubt there are some who take issue with even these directives
I'm guilty of this no doubt
with some composers who are not explicit about dynamics in their scores (for example, the composers who wrote before the pianoforte was invented) there seems to be a good reason to experiment with the dynamics or tempo, if not to commit an act of disrespect to the composer, instead to share a new interpretation that hasn't been heard before.
Some good discussion here. And if I still can't convince you guys that I am right, then so be it!