system
Given the following post, respond as if you're commenting on Reddit:
human
[ASOIAF / GoT] Why are the Unsullied castrated so young?

The Unsullied are said to be the most ferocious warriors in the planet, both from their iron will and from their physical prowess. Yet they're all castrated at an early age (the GoT wiki says they're castrated at age 5), isn't this counterproductive? 

Sure, I understand they're castrated so they never develop distracting carnal desires, but doesn't gelding them early also messes up their development because of the complete lack of testosterone?

You are essentially creating a group of castrati who will never develop the muscle mass they normally would and training them to be soldiers. 

Wouldn't it make more sense to castrate them **after** puberty? Once their growth is at least somewhat done and they can then just train to maintain their muscle mass.
gpt
A eunuch who is cut young will never have the brute strength of one of your Westerosi knights, this is true. A bull is strong as well, but bulls die every day in the fighting pits. A girl of nine killed one not three days past in Jothiel's Pit. The Unsullied have something better than strength, tell her. They have discipline. We fight in the fashion of the Old Empire, yes. They are the lockstep legions of Old Ghis come again, absolutely obedient, absolutely loyal, and utterly without fear.	”
– Kraznys mo Nakloz to Missandei and Daenerys Targaryen

It helps to condition them to make them "absolutely obedient, absolutely loyal, and utterly without fear"