1. There is no silver bullet.
Components are abstract concepts. The reality is not, therefore describing reality with components is always a trade-off between generalisation and precision. The only way to measure the quality of your model is to check whether it makes your life easier, f.e. by letting you explain what you have in mind faster.
2. There is no silver bullet.
Since components are abstract, their boundaries are arbitrary. A hammer is a component, an arm holding a hammer is a component, and a person holding a hammer is a component, too. Well, at least you can say so. The right way of identification is described in the point 1.
3. But there are consequences.
The act of naming brings a component to life and often sets artificial boundaries which people will obey. If you believe that a man with a hammer is component, you are likely to give each of your employers a hammer, and your employers will always carry them, as without it, they will feel incomplete. If you name a man a component, and a hammer, too, then you are likely to have a pool of hammers. If you identify IT, Sales and Business, you have just created siloes whether it was your intention or not.