Leaning technique A levels/gcse

Guys, no matter how long I spend learning, it feels very effective at first but then when I finish, after like couple of days i forget most of it,
I like working effectively... and working hard it's not a problem for me🙃
At the moment
I am starting to summarise everything down and put it into flash cards and try to learn it but the time I get to finish my flash cards I run out of time or I feel exousted 😮*💨 which is annoying.
Is there anything you guys do to learn more effectively?
Before a test?
And during lesson time?
Subjects I take
Biology A level
Chemistry A level

The most effective method I’ve learned is mind mapping. Look up Zain Asif on YouTube he has a really good step by step guide on how to do the mind mapping method. Good luck with your revision 😀