I found economics boring and dull. The actual content really isn't that hard imo. A lot of it (at AS, cant speak for A2) seemed like a lot of fairly standard responses. I've forgotten a lot of it now but i think the reason i bombed in it after getting fairly consistent 80% in mocks was because as soon as term time ended i didn't touch economics. I think i read the spec through on the bus to the exam because i hated it.
I dropped economics after the shame of a C. I set myself high targets. I don't think i would have been able to look people in the face after getting that (I am aware this is an overreaction but its just how i am). I'm glad my teacher left after my AS year because I think seeing him would have given me a pang of pain every time.
I'm not bitter about missing out on Oxford. It was really nice when I visited and I would have loved to go there but I consider it just punishment for my arrogance. I'm content with where I'm going and never expected Oxford (I don't think you should ever expect oxbridge because you will more than likely be disappointed). I'll be damned if i know what i want to do after uni. Hopefully, i want to have a decent amount of money and a job i don't hate.
With regards to EPQ. I know some people who were constantly working on their EPQ, most people doing one tbh. Whenever I'd see them they'd be beavering away on their laptop adjusting their power point or whatever. At the other end, there is myself. I wouldn't copy my ethic with regards to EPQ because I did not expect an A (was hoping for B at best and realistically expecting a D or C). I did all the practical work for my EPQ pretty quickly once I'd gotten into it and then wrote my report the weekend before it was due (in its entirety).
Playing with FBI data was quite fun (and you can draw some questionable conclusions for pretty much whatever you want) and learning R was nice since it'd been a while since I'd done any coding. So this didn't feel like it took much effort. Idk how long it actually took me to do this part because it wasn't really like doing work. I think you can do the majority of your research and stuff in a week or 2 if you actually go at it. A lot of people seemed to constantly be working on their EPQ but never really doing any work. They'd have it in front of them or they'd have a source but they wouldn't really be doing anything. They'd just be re-reading it or making notes when they already had too much content. EPQ is only 5000 words which really isn't many (it sounds like it is, esp to a STEM student, but its not). If you've got something to say then 5000 words is easy.
However, I was terrible at keeping a log book (I made it up almost entirely) and my report was written all at once at the last minute. Don't do this. Something I've come to believe is that if something is worth doing then its worth doing well. Half-****ing things isn't worth it. ~50% of your mark doesn't even come from your report because the exercise isn't about the report. The purpose of EPQ is to try and get you to practice self study and research skills. Personally, i loathe timetables and schedules which is not good for EPQ because you get a decent amount of marks for setting and sticking to timetables and schedules (i suppose i lied and said i did but its probably not a good idea to do this).
A huge problem I had with wanting to do a maths based EPQ is that you're expected to use at least 12 sources and evaluate their viewpoints. Maths doesn't really have opinions because its generally right or wrong and there's not much to discuss. If i didn't have an ethical element to my EPQ then I wouldn't have been able to do this at all (fortunately, with the whole black lives matter movement and stuff it was easy to get lots of angry opinions and contrast them to the data I had. I think having this ethical argument really was my saving grace since that's what EPQ is about). The vast majority of my report wasn't about maths at all which is why I don't think it helps with maths applications.
However, for engineering or physics i can see it being useful. I think and engineering EPQ about designing (and probably making) a thing would work very well and could go down excellently in an interview/personal statement. This would, however, actually be a lot of work (i imagine)
Argh, I'm not happy with this post - it's all over the place and unfocused. Oh well, I hope it helps in some way. Basically, I don't recommend EPQ for maths - it's not a natural fit and you likely wont get concessions for it. EPQ can very realistically be completely finished in 3 weeks if you work for a few hours most days but its not supposed to be. The purpose of an EPQ isn't the report - its the process. So while it isn't too much work its still work and I don't think it helps.