As someone who's a part of one of the three 'ultimate' rps I feel a little less naughty in commenting, but;

Surely the whole point of a sample post is to show off how you write in an RP, under that consideration, an IC post from another RP makes 'more' sense than one you just think up. Technically one you just write out of the blue isn't an effective sample of your writing, at least if we were to apply experimentation principles (i.e. collecting evidence from a source specifically designed with the test in mind).