Data will be secured by data source. -> Use DataSource as top folder.
Most queries will include a filter on the current year or week -> Use \YYYY\WW\ as subfolders.
Common Use Cases
A common use case is to filter data stored in a date (and possibly time) folder structure such as
/YYYY/MM/DD/ or /YYYY/MM/YYYY-MM-DD/. As new data is generated/sent/copied/moved to the storage account, a new folder is created for each specific time period. This strategy organises data into a maintainable folder structure.
Reference: https://www.serverlesssql.com/optimisation/azurestoragefilteringusingfilepath/