Limit the faffing. The best way to realise what you know and don’t know is to try some past questions, or old mocks or whatever resources are available.
Say your child is doing genetics in biology. A lot may be new, so will feel content heavy. I would suggest reading over the course notes, jotting down major topics then going straight into questions, using the course notes as a guide.
Children could spend hours writing, re writing definitions and making them pretty with highlighters and trying to memorise them. But the best way to make DNA replication, transcription and translation “stick” is to apply it, understand it, then fine tune definitions if necessary.
Similarly, you can write how thymine is a nucleotide base in DNA but it’s uracil in RNA 20 times, or get it wrong in one question about base pairing and never forget it.
It could take a while to perfectly memorise the difference between autosomal dominant, recessive, X-linked inheritance but if you’ve done a whole heap of punnet squares and know how to apply them, it’s a lot easier to answer harder questions about probability and chance related to them.
This process should be more taxing than writing, rewriting, reformatting study notes but will be more efficient.
After knowledge has been applied and content understood - then go back and work out what needs to be rote learned, or the student needs reminding of and make study notes at that point. These will be much less hefty than just the content written out multiple times, over and over.