“Too many cooks spoil the broth.”
Meaning: If too many people are involved in a certain task, or the same thing, there is a good chance that it will not have good results.
Imagine five or six people helping each other cook in one pot. One person might decide to add sugar, while another, salt, and yet another, a spoonful of spices. The end result would most likely be disastrous.
This idiom can be used in any instance where you feel like too many people or opinions are not necessary.
Broth: a thin, watery soup, like the liquid in the image below. It is made from water that has been boiled with meat, vegetables, rice or barely.