In UART learning of string reception with end mark, I had to start with blocking code to get the confidence level of the pupils that the UART Port indeed works and then I assigned them the job of creating a sketch using non-blocking code.
So, which one is important that depends on the situation.
While the @hg1001 has hardly any knowledge on programming, we are enganged in competitions among ourselves as to which one is optimum.
Why not asking the @hg1001 to cretae a sketch that turns the Servo by 30 degress?