In British English, the rule is clear. We use 'on' for single days and 'at' for holidays/festivals which last for two or more days. This includes 'weekend'. For example: on Wednesday on 24th June on your birthday on St Patrick's Day on Christmas Day on New Year's Day on Easter Sunday at Christmas at Easter ( a Christian festival) at Ramadan (a Muslim festival) at Hannukah (a Jewish festival) To answer your question, we say 'at Christmas' to refer to the whole Christmas period, which lasts several days (or even weeks). This is different from 'on Christmas Day', which refers only to 25th December. Likewise, we say 'at Hallowe'en' to refer to the whole period of several weeks when everyone seems to be obsessed with pumpkins and spider's webs and suchlike. I hope that makes sense. It's certainly a logical and consistent system which makes sense to everyone around the world who speaks or has learnt British English. American English is different in this regard, as American English does not tend to use 'at' for periods in the calendar. This is why speakers of AmE will say 'on the weekend' as opposed to 'at the weekend'.

In British English we tend to use AT for festivals, Eg. AT Christmas, AT Easter. And we usually say AT the weekend, whereas Americans say ON the weekend i believe. It 's a little confusing for English learners dealing with American English vs. British English

No I don’t think so, thank goodness It’s complex enough haha 😊

Thank you Gonz and Toni :) It was great help. Have a good day!!

What do you mean "at Christmas"? In English I would say "You will get your presents on Christmas" I might say "You will get your presents at Christmas time." I'm American though, maybe Europeans use at for Christmas all the time, not sure tho.