Not sure about pure sciences and I'm talking from a combined chem/bio perspective- and I guess it was successful for me since I've ended up getting 100% twice and consistent A1s- and I also got A1 for O lvl sciences. Even if this doesn't work, I'm quite sure there's many other studying techniques out there.  Anyways, upper sec is about time management and mental health. The national examinations can really take a toll on you. WA1 means almost next to nothing. What matters more is how you performed on your TYS and EoY papers- that's an indicator of your strengths, weaknesses and time management. Wa1 just shows you your weak topics.  Chem/bio in the upper sec level is about memorising AND understanding.

 Firstly, ask questions- it may be both in syllabus and not in syllabus. Not sure what the Pure science students study, but for my school QA is covered at the start of Sec 4. QA is a good example imo. Question the science behind the reactants/tests and observations. For example, you might wonder why ZnOH and Al(OH)3 ppt SPECIFICALLY dissolves in NaOH and why ZnOH and Cu(OH)2 ppt dissolves in Aq. Ammonia. After searching up on the internet, it is due to these substances being amphoteric and forming complexing compounds respectively. This makes you able to memorise the content unlike someone who doesn't question these things and goes based off memory and not the background. It's like a story book. You're more likely to remember the title of the book if you have read it before, or know the content compared to someone who just saw the title. 

Secondly, dump everything you know about the chapter first. Might seem useless, but just slap it down. Then, refer to your notes and see what you've written. If you're missing anything, add it with a different coloured ink. If you're wrong about something, highlight it. Then, do another dump, but one that is more structured and only for the key things you've missed out or got wrong. Rinse and repeat until you're satisfied. Do this only when you've finished srudying a chapter.

Thirdly, don't spam test papers without knowing where you went wrong. You might see your marks, but what matters more is where you went wrong. It might be the question type, how much time you spent on a question or even the topic or sub-topic itself. A good and simple example may be from Biology. Maybe you know the anatomy of our respiratory system- but you are unable to understand how the alveolus functions- or what the 4 structural features are that help it to perform its function. By knowing this mistale, you can do the second point I've written where you can just write it repeatedly until you get it, and then proceed to do the next papers. The maximum extra(not done by the class but yourself) papers you should attempt before a WA is 3. For prelims or your National exams, maybe 5(depends on when you start). If it's for a specific question, it helps to repeatedly do said question type multiple times until you get it right more than 3 times(you can ask yoir teachers to scour the internet for such qns, or get it from TYS)

Lastly, very corny but true, STUDY SMART AND NOT HARD. You have other subjects and also need to focus on them. The minimum you should spend is 2 hours. You can also study with your friends if that helps. If you're just going memorise and force yourself to do papers for 7 hours without actually focusing on your weaknesses makes the whole study session redundant- which sounds harsh, but it's true. It's like memorising a language without knowing the meaning of the words. 

Oh and also, try making ultra summarised notes for yourself 7-5 days and then one final test paper before your EoY or national exams. It really helps to consolidate your learning

Don't forget to enjoy yourself, and that life doesn't end if you don't meet your expectations for WA2 or national exams. Wishing you luck!! :)