This method you said is general and probably many people use this. But the most important problem is how to do it.
I know an instrumentalist who has been playing professionally for almost 10 years, but if you ask her to make a 1-minute piece, she has no special idea for it. Because this person has only learned to play based on an available piece, to put it in front of her eyes or memorize it and move her fingers according to the written notes.
Creating a new piece is not something that is done by chance and based on inspirations, to randomly choose a chord progression and start dressing up and adding bells and whistles to it. This method is not accurate. In the exact method, a solution must be thought of for every second of the piece, and the role of inspiration in the production of the exact piece is almost zero.

 

Chose a scale and start playing chords and individual notes until something catches your ear. Alternately, you could play either the chords or the notes, and then add the missing melody/harmony part later.

 

This is exactly what my signature says.