This is definitely one of those questions that's hard to give a definitive answer to. It really depends on what you're using the YAML for and whether not having it on all relevant notes would prevent you from accomplishing your goal.
Let's say I have my watched movies in Obsidian. I have basic YAML like IMDB link, genre, and year released. Later, I decide I want to see what directors I have watched the most. In this instance, not having the director YAML on all of my movies is something I would want to fix.
Continuing the above example, I would do two things to make adapting the new structure easier. First, I would update my template for movies to automatically include that field for any new movies I create. Second, I would probably use Dataview to create a utility page to identify movies with no director. The logic of the query would basically be "select all from movies where no director". That way I could systematically update my existing notes without having to look through all of them individually.
Hopefully this gives you a couple of ideas. If you have any follow-up questions, let me know!
Hey there, sounds like you've never driven a car before. No shame! I'm more than happy to clear up any confusion.
Typically, roads with a single lane in each direction are not elevated off the ground. Meaning there is a location known as the "side of the road" where people are able to pull off if they have car trouble or are impeding a huge line of traffic. Unfortunately, this "side of the road" i mentioned previously is typically dirt, meaning that it's very dangerous to pass from. In many regions where common courtesy exists, pulling over to the side of the road (refer to previous sentences if still unsure) is very much appreciated.
Hopefully this helps! If you're still feeling a little slack jawed about the whole thing, feel free to let me know :)