In Year 10, I completed IGCSE English Language and Mathematics in Oct/November.
In Year 11, I completed IGCSE Biology, Chemistry, Physics, English Literature, French, AS Mathematics and Thinking Skills in Oct/November
In Year 12, I completed AS Biology, Chemistry, Physics, English Literature, English Language, Economics and A2 Mathematics, A2 Thinking Skills in Oct/November.
In Year 13, I completed AS Business Studies, Global Perspectives, General Paper and A2 Economics in May/June and A2 Business Studies, Biology, Chemistry, Physics, Further Mathematics, Thinking Skills, French in Oct/November.

I learnt a number of interesting things on this journey:

1. Challenge the assumption of the “status quo” in terms of how many subjects and how fast you can learn. The school curriculum and indicated time frames are only indicative. Learn based on your own schedule, passion and pace if you can go faster than the “status quo”.
2. I largely took biology, chemistry and physics because I perceived them to be rigorous, challenging subjects that expanded my mind but had an early feeling that this pathway wasn’t the one for me. My initial dive into AS Economics helped to unlock an entirely new academic trajectory that I ended up loving at Harvard (my degree ended up being in Applied Mathematics and Economics)
3. Teachers are absolutely wonderful and supportive but sometimes give you advice based on what is easiest for them, rather than what is best for you. Be careful and discerning.
4. The world doesn’t operate on absolute level of achievement when it comes to university admissions but relative levels of achievement. If everyone is taking 4 A levels and you take 10 A levels, it will probably help you justify your case you are going above and beyond the call of duty (something US universities appreciate). Don’t follow the herd or the average person, because otherwise you will be exactly like the herd.
5. A strong foundation in Mathematics/English is absolutely fundamental to success in most fields. My strong background in English (Top in World IGCSE English Language, Top in World A Level English Literature, Top in NZ English Language), debating, Model UN and public speaking enabled me to quickly succeed in subjects like business studies, thinking skills, general paper and global perspectives which required clear, concise argumentation and logical reasoning. My foundation in Maths helped me with Physics, Chemistry, Economics and Business Studies.

Hope that helps!