Javascript OnScroll performance comparison

So let's say I want to add some expensive action on my site triggered by scrolling. For example, I'm using parallax effects in my jsfiddle.

Now I keep reading it must not be bound to the event directly, sometimes followed by snippets that are meant to be better. Just some examples:

1. Attaching JavaScript Handlers to Scroll Events = BAD!
2. How to develop high performance onScroll event?
3. How to make faster scroll effects?
4. 60FPS onscroll event listener

What they say is basically don't do this:

  // Bad guy 1
  $(window).scroll( function() {
    animate(ex1);
  });

or this

  // Bad guy 2
  window.addEventListener('scroll', onScroll, false);
  function onScroll() {
    animate(ex2);
  }

But use timeouts, intervals, requestAnimationFrame and whatnot, for example:

  // Good guy
  $(window).scroll( function() {
   scrolling1 = true;
  });

  setInterval( function() {
    if (scrolling1) {
      scrolling1 = false;
      animate(ex3);
    }
  }, 50 );

So, I went and added the options I found in the links above to a jsfiddle that tries to compare them by adding a counter to every approach, like so:

  // Test
  $(window).scroll( function() {
    counter = counter + 1;
    // output result of counter
    animate(ex1);
  });

Best to check the complete jsfiddle or use this for old browsers: Scrolltest (the same, just not on jsfiddle)

Outcome: Everything that works smooth is about the same number of calculations. If I can live with choppy effects, maybe I can safe some resources. And against everything I read, this seems logical to me!

First question: Am I missing something or is this a valid test? If it's invalid, how could I test correctly? Edit: To clarify, I want to test whether any of the above methods save performance at all.

Second question: If it is valid, why is everyone nervous about onscroll? If fluid animations require 5000 calculations over the complete site, there's no way to change it anyway?

(Well, sometimes I use checks to determine whether an object is in the viewport or not, but honestly I don't even know if those checks aren't as expensive as the prevented code itself, especially if they involve five different variables such as offset, windowHeight, scrolltTop, getBoundingClientRect and outerHeight...)

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