Your rule of thumb should be: add value to a note every time you touch it. This could include adding an informative title the first time you come across a note, highlighting the most important points the next time you see it, and adding a link to a related note sometime later. By spreading out the heavy work of organizing your notes over time, you not only save time and effort, but ensure that the most frequently used (and thus most valuable) notes surface organically, like a ski slope where the most popular routes naturally end up with deeper grooves.