As for the brakes, what you said is all dead-on. As for the valves, typically you have to tighten them. If you overtighten an adjustable valve it will cause the valve to leak and you will get misfire. You are not loading the rocker arm against the spring, you are loading it against the tip of the valve stem. If it were spring loaded between the stem and the rocker arm then you 'could' load it up against the rocker, but they aren't built that way.
: ...can I get your opinion on this post when you get a minute? TIA....