My first two sheets of 4x5 came out dark and red. I loaded it just like they said - notch to the upper right. That was the mistake. When you talk about how to orient two things with each other, you have to reference them to each other. Saying "upper right" is only worthwhile if there is only one possible orientation of the holder itself, which is demonstrably not true. In fact, when folks tell you to put the notch in the upper right, they mean " put the notch in the upper right when the holder is oriented such that the darkslide is removed by pulling it downward." However, if you are changing film in a bag, you probably don't pull the dark slide down and slide film down in the top, that would require a very large bag and something to hold the top up to form a large enough cavity for the holder, slide, and film. Instead, you probably hold the holder in your left hand with the film opening to the right, pull the darkslide out to the left,and slide film in from the right with your right hand. In this case, the notch goes to the LOWER right. Stated another way, if the darkslide is at the top, the notch is at the lower left. Of course, you could rotate the film by 180 deg and still get a normal image...
Probably a more foolproof way of stating the correct orientation is to note that the corner of the film closest to the notches should be clockwise from the notches.