Hi, I'm asking this on behalf of other non-native English teachers at my school, because the answer is important in relation to a recent examination question.

Is the following statement, "She hates to work at weekends" valid grammar?

It sound a bit odd to me. To me "She hates to work on weekends" or "She hates working at the weekend" sound more natural to me. I would think "on" is better in all cases, but "at" seems to sound okay in some instances but not in others. But I don't know the exact grammatical definitions in these things, and I don't know if there are variations here between American English and British English (I don't know American English that well). So if you can help, please do so. A grammatically definitive answer would be appreciated, because this is related to an exam. Thank you.

I'm a native British English speaker and "She hates to work at weekends" sounds fine to me, as do "She hates working at the weekend", "She hates working weekends" and various other permutations.

"on weekends" and "on the weekend" are not natural to me. I can't really advise on US usage, but looking at Google news hits it seems there's a definite bias towards "at" in UK publications and "on" in US publications.

I'm not sure there's any "grammatically definitive" answer here. The question seems as much to do with idiomatic preferences as grammatical rules.
Oh thanks. I'm from New Zealand originally. We have British style english, but I think American style english has become mixed in a lot because of media, so it's all rather confusing to me. Emotion: smile