I think it might depend on the writer's style, as well. I used to write sex scenes that lasted for page after page. But then I changed some style issues in the structure of how I write. Lost a lot of verbiage that wasn't really necessary, and sometimes got in the way of the action. Now the scenes, unless they get interrupted and then resume (which happens.
) tend to run shorter, but more intense.
It really is up to your style of writing, the situation of the scene, and really, what you're internal editor suggests to you. I don't think a short scene is better than a long one. Or a long one better than a short.