Design is an iterative process. You start with some assumptions, design something , find gaps, and realize a lot could be done.
Some design outcomes can be corrected, some can be fixed and some has to be re-done.
Nevertheless, design is an iterative process of dreaming, seeing, learning, doing, understanding and improving.
Design can be learnt, design can be taught and design has to be practiced to master it.
When you are learning, make sure you learn from someone who is practicing and not preaching.