I totally feel like that with Methods as well! It's the subject I spend the most time on and I don't really see the value-for-time relationship I'd like.
It's worth it to study for this subject, though, as it can open up so many doors for the future.
I think that working on questions that aren't in your textbook is a good strategy - you can be doing practise exams, application-style questions, watching youtube videos and doing so many other useful things
In case you're interested, I recently posted something on my blog that relates to how I study for maths. Feel free to read it here -->
https://chamomileandcolour.wordpress.com/2019/10/10/how-i-revise-for-maths/ .
Hope that helped!