When it cums to Anal sex, stamina is thing you have to build up because pornstars and ass sluts always want you to keep on going! One girl will give a good ass eating before an anal fingering and follow it up with some lesbian strap-on anal sex.
And that includes eating it, fingering it, and cumming in it.
Let's put it this way, even if you keep fucking until every wrinkle of her rectum is pressed out as smooth as fresh concrete, she'll want you to keep on fucking her up the ass because it feels so good.
That is what makes Anal Sex so much better than simple missionary style fucking.