system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Harry used three wands to stun Greyback with a triple spell. If that works, why doesn't everybody use many wands? Were the spells each as strong as a single wand would've produced, or did Harry just split the power of one spell into thirds?
gpt
Harry was 17 at the time, and had never paid much attention in his classes. He had three wands available, so he gave it a try, but the number of wands didn't change anything. One wand or three, a spell is only as powerful as the wizard or witch who is casting it. Otherwise, wandless magic would be impossible. 

However, since Harry didn't know that, he likely believed that the spell would be stronger. Any student with an OWL in Charms knows that the more you believe in a spell, the more force of will you exert on your magic, the stronger the spell will be.

So it was not the wands that gave the spell triple power, it was Harry, using triple the power that he would otherwise have used.