I wish I had that level of planning. I literally just do things when it comes to development. I might randomly hop on Blender and the end result could be anything from a level prop to a new weapon. Code is probably the one thing I somewhat plan out on paper or my whiteboard especially if it's a complex system. I still feel for anyone who might ever have to read the source code to my games haha.
The fact that I can't draw a straight line means any art assets I do are purely spontaneous and often get revised or scrapped multiple times before a final version is imported.