Hey Alec, thanks for the question!
You don’t have to link a new note with every other note that’s related to it. It’s enough to link to those notes that are most obviously related. Moreover, you don’t have to create all of the links all at once. You can create links over time. If you create a new note today and in three months you happen to stumble upon this note again and notice that it’s related to some other note, you can create a link at that time.
Think of it this way. Imagine each note is a city and the links are roads. If a country has 1000 cities, the government doesn’t need to built a dedicated road for each pair of cities that people want to travel between. As long as you can get from any city to any other, the network of roads is useful.
Again, all cities need to be connected to the road network, but not every pair of cities that people may want to travel between needs to be interconnected by its own road. Some cities function as hubs and sometimes if you want to go from A to C, you have to go through B first. It’s not a problem.
If later the government notices that a ton of traffic is going from A to C, then it makes sense to create a direct road from A to C. Otherwise, the intermediate step through B is alright.
It’s the same with your Zettelkasten. If you notice there’s a strong connection between a note A and a note C, create a link between them. Otherwise, it’s okay if you can go from A to C through an intermediate note B.
Maybe you’ve heard of the concept of six degrees of separation, which says that you can go from any person on this planet to any other using six or fewer social connections. In other words, any two people on this planet are at most a friend-of-a-friend-of-a-friend… 6 times. It’s the same principle in the Zettelkasten. As long as you keep connecting each new note with a handful of links, you’ll be able to reach any note from any other by just following very few links.
Hope this helps! And thanks again for the great question!