Don’t you have more HDD than ports available on the hba? Or are you using the data ports in the motherboard as well? Make sure the PSU has enough power plugs available for all of that stuff or buy high quality, not molded splitters!

While it doesn’t use a fixed folder structure, you can decide the folder structure for each file based on any attribute. So all 2023 receipts for car a can go to “car a/receipts/2023” or “receipts/2023/car a” of whatever you wish. Really flexible! And if you change idea, you change the scheme and all the files are moved where they belong!