Particularly, there are 2 variants of $\Rightarrow$, one is $\Rightarrow^*$ and another is $\Rightarrow^+$ which are used in derivation of strings using the productions of the grammar.
As stated here, when $\Rightarrow^*$ is used, it means derive in 0 or more steps and when $\Rightarrow^+$ is used, it means derive in 1 or more steps.
What I don't understand is what is the use or importance of $\Rightarrow^*$ operator?. It just replaces the head of the production with the head itself.
Is it that the $\Rightarrow^*$ operator is just there to define operators in some standard way or it actually differs in the way it is used as compared to $\Rightarrow^+$?
Also, while deriving strings, to skip some obivious steps(like replacing multiple non-terminals in a string with their respective terminals), should I use $\Rightarrow^*$ or $\Rightarrow^+$?