Its your preference which way you want to do the task.

but some task for instance do something in powercli you must have to use powercli.

as VirtualRay mentioned it is down to you preference but some things are much much faster in different tools and the exam is blisteringly fast. There are also points where you can only use one tool. My advice is make sure you can do every single tasks mentioned on the blueprint via command, the gui and powercli where possible.