I feel exactly what you're saying, bro. For me, Methods doesn't seem worth putting in any extra effort at all because I would need a 40+ raw to kick another subject out of my top 4 (English, German, last year stuff) and in a simple cost-benefit analysis all that effort isn't worth it. It's probably worth my extra time maximizing my score in English.
While many would disagree with me, I think it's fine to have an idea of what you main top 4 will be and give your effort towards that. If I get an extra three study scores for both Chemistry and Methods, my predicted ATAR would go up 0.10. Now let's just say I invested those 6 points across 3 each for English and German... and I get an ATAR a full point higher. That's 10x as much an impact simply because they'll be contributing the full score to my aggregate rather than the 10%.
Don't get me wrong, I'm not saying you should drop all effort in Legal. For me, I continue to try my best in Methods and Chemistry, but I accept these simply aren't my stronger subjects. In this sense, I think an approach similar to the one I'm referring to is 100% fine, and you should do it if you think it will help you go where you want to go in terms of maximising your scores.
tl;dr: healthy and reasonable approach, just don't stop trying altogether because they're still safety blankets