You probably don’t know what you will use obsidian for and your needs with change over time so it is nature to add structure to Obsidian as you go. I sort of think of this as “coats of paints” added to a task.
The first time I do something I don’t try to add much structure. Just throw a note into Obsidian and add a tag to find find it. But then, if I do a similar thing and find it again I clean up the not a bit more and maybe link it to other things so structure and use go together. I don’t have a fixed rule for how much structure I add just “enough to not distract from the task I am doing.