Best data structure for daily logging – and help with data formatting in Datajar

i’m building my first shortcuts using Datajar/JSON for storage. The shortcuts will track habits and other daily datapoints. My initial idea is to store the values in a structure like this:

journal > YYYY > MM > dd > key > value

and for some more keys that will include multiple values

journal > YYYY > MM > dd > key > subkey 1 > value
journal > YYYY > MM > dd > key > subkey 2 > value

Is there from any perspective, like performance or other, a better structure?

Also, I have trouble getting the data stored where I expect it to in Datajar. I’ve tried different custom formatting for the date part, like or with the same result:

journal > 2020 > 11 > Index 1 > key > value

What am I doing wrong?

It might be useful to share an example shortcut and details of the data types you are utilising for different parts. These could both influence how data is being stored, depending upon your method of entry.