So far I happen to be really good at CARS, and it's probably because I was a philosophy major. I've thought a lot about this and I'm still working on my own thesis for what makes a successful CARS test-taker and therefore what would be a good training strategy, and the best thing I've come up with so far is being trained to
identify and
create good and bad arguments. I think that's all it takes. I'm still working on it though!
I think that if you know how to write a good argument, then you will know how to quickly spot what the author is trying to say, what they are using to support it and see where their points are strong or where they are weak. I think everything else should follow from there.
I wonder if simply analyzing passages very slowly and meticulously to build these arguments over and over again would help far more than just doing tons of CARS passages using these little hacky techniques. On the same token, perhaps it would help to write your own arguments and have someone who is more skilled critique them to help you get better and better at making them. Hire a philosophy grad or a recent LSAT test taker (I've heard that physics and philosophy majors do the best on the LSAT)!
Just an idea!