How many hours to work on each subject per week? Year 12

In year 12, how many hours should you work (on average) for each subject per week? I've seen people on TSR working for many more hours than have been recommended by school. I currently have 21 frees over a fortnight and then obviously will be willing to work at home. What's an average number of hours to spend and review work at this stage in the year?

You have 21 frees over 2 weeks!! I have 9!

Year 12, 3 science and maths. Feeling sick about it, i think ill swap them.

In year 12, how many hours should you work (on average) for each subject per week? I've seen people on TSR working for many more hours than have been recommended by school. I currently have 21 frees over a fortnight and then obviously will be willing to work at home. What's an average number of hours to spend and review work at this stage in the year?

I got AAAB in AS and I did sciences and maths and a language so "hard" subjects and I did not once count how many hours I was doing!!! It's irrelevant. Whether you spend 3 hours a day or one, my advice is first of all, make sure you understand the principles in class and then rewrite them at home because it will help with remembering. Understand and remember. So personally my class notes were to aid understanding and then I rewrote my notes again everyday from memory at home in a notebook and then filled in the gaps of what my memory missed out by looking at my class notes. It's amazing how much we forget at the end of the day. If you don't want to do that please at least review your notes when you get home!!
This means I took like I don't know half an hour or an hour a day? Roughly 3 hours a week more or less on my own revision not including homework.
I would suggest exam questions as you go along if you have time. I didn't... I was always too tired for some reason.

I got AAAB in AS and I did sciences and maths and a language so "hard" subjects and I did not once count how many hours I was doing!!! It's irrelevant. Whether you spend 3 hours a day or one, my advice is first of all, make sure you understand the principles in class and then rewrite them at home because it will help with remembering. Understand and remember. So personally my class notes were to aid understanding and then I rewrote my notes again everyday from memory at home in a notebook and then filled in the gaps of what my memory missed out by looking at my class notes. It's amazing how much we forget at the end of the day. If you don't want to do that please at least review your notes when you get home!!
This means I took like I don't know half an hour or an hour a day? Roughly 3 hours a week more or less on my own revision not including homework.
I would suggest exam questions as you go along if you have time. I didn't... I was always too tired for some reason.

did you do a ll 3 sciences?

I got an E in maths at AS Level (overall C2 brought me down), Would you have any really good tips for revising maths? By the way I am not naturally that great at maths, I need it for the uni course I want to do so I couldn't drop it and therefore I need to do a lot of revising to reinforce it.

Make you sure you pay full attention to the explanation, that's the most important part!! Don't bother revising from questions you've already done....write down the general principles/key facts that will enable you to answer any question. Understand these and I feel like you should be fine. One does not really "revise maths". Use examsolutions videos if you get stuck as well. It's really common to make silly mistakes so make sure you check questions you've done properly and never get sloppy in an exam.... I hope that's enough for you. To be honest I was naturally good at maths but with the right technique that works for you, you can do it!!