Weight on different areas of a paper airplane can help it fly farther for longer, or it can cause it to crash to the ground. To a certain point, the heavier a paper airplane is, the better it makes its way through the air.
Adding weight to the center of the airplane helps it fly a little farther, but it does not provide for the most distance. Adding weight to the rear of the airplane causes it to fly up instead of out. The ideal place to add weight is in the front. This creates a longer travel time than that for a plane without any added weight.