It depends on the magazine, Shel, and on the department/section within the magazine.
A feature article could be the author's or staff writer's own recipes, for instance. Or they could be that of a chef who's being profiled, or a collection of ethnic or otherwise bound-together recipes, etc.
For instance, in the September Food & Wine, Marcella Hazan has a short article detailing her latest take on Marinated Fish with Salmoriglio Sauce. Obviously, that's her own recipe. However, Marcella could just as easily have done an article about the foods of Sicily, which would have included traditional recipes, recipes from restaurants, and maybe her own take on some dishes. Or I could do a piece in which I interview Marcella about, say, her ten top favorite Italian dishes. Those ten recipes may, or may not, be original to her. They certainly wouldn't be original to me.
The reputable, high end magazines (Bon Appetite, Gourmet, Food & Wine, Saveur, Food Arts, etc.) have test kitchens, where every recipe is rigorously tested before it runs in the magazine. Gourmet's test kitchen, in fact, is the envy of every chef in New York because it is incredibly well stocked, and because it's operating budget is, for all practical purposes, unlimited.
Problems with printed recipes can arise from several directions, however.
1. Not all cooking magazines maintain those standards. Very often they have just lifted a recipe from another source---warts and all---and run it as original. If there's an error in the original, it gets reprinted. While you do see this more often on the Web, it's common enough in print media as well.
2. Those involved in proofreading can fall down on the job. Often enough you see recipes, even in the high-end pubs, that have egregious errors. Ingredients left out of the ingredients list, or steps left out of the directions, etc. In the top magazines such errors creep in after the recipe leaves the kitchen.
4. When errors are discovered the high end books take immediate steps to correct it in the very next issue. However, if you don't see the correction, your copy of the recipe will still be wrong.
Somebody once said the amazing thing about a dancing bear isn't that he's so graceful, but that he can even dance at all. So it is with recipes. When you consider the thousands of recipes that are printed every year, it's amazing how few actually do contain errors.
They have taken the oath of the brother in blood, in leavened bread and salt. Rudyard Kipling