In English, in what situation or occasion do you use "copious" instead of such as "a lot"?

I would use copious in writing but very rarely in speaking unless I was being sarcastic or funny or something. Few people would ever use 'copious' in speech unless it was an academic lecture or something of that sort. A lot is much more casual. You wouldn't want to use 'a lot' that much in an essay haha.