Nice to see somewhat knowledgable commenting on this issue and actually test things out. It's very easy to say "meh, you haven't done a scientific test so it's probably placebo", but remember that you're being equally un-scientific in such an analyse.

When so many users are reporting improvements you (aka. Google) owe them to get to the bottom of it.

I also find it surprisingly that nearly no-one posts information about what phone they tested it on. Android ships in so many variants that it wouldn't surprise me if it only works in some of them.