Main point: Second brains are great in particular because they require no structure.
Seconds brains have reached quite the hype. Both with tools like RoamResearch, Obsidian and friends. Needless to say, it is a good tool. Since I started building my second brain, I have been journalizing more often than not. This is healthy for me.
On of the strength about second brains is that they are naturally without structure. That is, thoughts do not need to go into particular folders. They can go in todays journal. If it makes sense, they might occupy their own file. They might be constituted in a tag, and expanded to a full file whenever there is juice enough to do so.
This is not to say that cleanups and organization is not possible and should not be aspired to. It is just another process, saved for another time. Like a boring sunday afternoon with nothing more important to do, whenever they come. A deep consequence of thinking this way is also the acceptance that thoughts and ways of doing thins change on a structural level. For a personal second brain this is perfect. Tools I need naturally emerge from my text. When I don't need the tools anymore, they evaporate.
One aspect I am especially keen about is what leverage I will be able to get: Will I be able to derive some deeper truths about myself? Will I be able to find insights I was not able to see before? Currently I am merely producing the data. Along with this, my work with Spor.ai hopefully will bring forward tools needed for such inspection.