When I was a Scout we were on a training backpacking trip. A group of older Scouts repeatly got ahead of the main group by a fair distances. Finally the leaders got tired of it and had us “younger” Scouts put some rocks into there packs to slow them down. Well it didn't slow them down that much, but when they got to camp and found the rocks they were amazed. It was estimated by end of the hike something like 25-35 pounds of extra weight was added to there packs. The older Scouts said something like we noticed our packs felt heavier but not that much heavier. Don't worry this was all in good fun, at the time was not considered hazing and the older Scouts actually enjoyed bragging about carrying all the extra weight. As this was over night training hike the weight we were carrying was far less then what we carried when we did Philmont or the Grand Canyon twice. We were a well trained and respected group.
The lesson … if you get to far ahead of the group, expect some extra weight will be added to your packs to slow you down.