In many movies, it's intentionally not cut so that you can tell it is real. Porn stars do
do that often, but they also subsist entirely on liquids for two days before a shoot, take laxatives, and use enemas before scenes. They are very clean before a scene. Sometimes, if a performer's preparation isn't going well, the scene has to be rescheduled for another day.
They are pros, they are experienced, they receive expert advice from other pros, and are paid well to do what they do. Unless you also have access to advice from adult performers, have practiced cleansing yourself before it matters, and have the dedication it takes to spend days preparing for your "scene", I would advise against doing what you see in porn.