Meg1970 it makes it much easier to dial in a new bean. When you dial in new beans you will want to lock in as many parameters as possible.
As starter, aim for 1:2 ratio within 25-30s. So you grind 15gr of coffee ground then pull 30gr of espresso. Scale helps you with that, it is ok for have 0.2gr or 0.3gr or even 1gr off mark, but not 3 or 5gr.