If a task needs to be done, it can be a disadvantage if too many people are trying to do it. People all have their own ideas and each person will interfere with the efforts of the others. A smaller number of people will find it more easy to form a common plan and co-operate with each other.
The proverb states that a cook was preparing broth for the evening meal. A second cook entered the kitchen, and seeing the pot simmering away, wondered whether the salt had been added and bunged some in just in case.
No sooner had he left than yet another cook came in, made the same guess and also added some salt.
There were six cooks on the staff so you can imagine what the broth tasted like.
chadad.