When you give 15 people energy through names on paper at the same time, the energy will get divided among all of them, so each one will receive less than 10% of total energy !!
I am not sure what are their energy requirements, but we don’t suggest to write so many names together !!
You can instead ask images of their water bottles so that you can energise that it will take few minutes to energise all one by one. And when they drink this water multiple times throughout the day, they will receive more energy shots !!