Dynamic segments transition

i have read from the officia doc of emberjs 2.6 that :

Note: A route with a dynamic segment will only have its model hook called when it is entered via the URL. If the route is entered through a transition (e.g. when using the link-to Handlebars helper), then a model context is already provided and the hook is not executed. Routes without dynamic segments will always execute the model hook

so i tried something to see my self how its work :

post.js

import Ember from 'ember';

export default Ember.Route.extend({
  model(params) {
    alert("executed");
    return this.get('store').findRecord('post', params.post_id);
  }
});

index.hbs

        post.title

index2.hbs

        post.title

So when i open index.hbs and click on the link, the model hook is not called, and that what the doc confirm.

But When i open index2.hbs and click on the link, the model hook is called, even if its is a trinsition, not a link reload.

i can understand the second point because i give the route an id, so its use the id to fetch post from the store, but why is this point not described in the doc?