Existing symbols in the libraries can be utilised in new components. In fact, this is a key concept of our libraries.

If you have a series of resistors, why have a new symbol and footprint for each one when they all use the same shapes? Just re-use the same two symbols as many times as you like. The only time you may need to change a symbol is when the footprint pitch changes or when you use a surface mount variant instead.

As well as speeding up the original creation of new components, this can also help in rapid updating if you find a problem with a symbol. For instance, if all your resistors use the same 0805 footprint and you find a problem with one, correcting that footprint and updating any component in each design using it will put right all the components that use the footprint within the design as the internal copy in the design will also be updated.