Economics tells us that the right thing to do is run the factory until the last item produced is being sold at marginal cost. In other words, keep adding until it doesn't work any more.

In fact, human behavior tells us that this is a more permanent effect than we realize. Once you overload the user, you train them not to pay attention. More clutter isn't free. In fact, more clutter is a permanent shift, a desensitization to all the information, not just the last bit.