Item and Item Group DocTypes have Purchase and Selling Defaults (Default Expense Account, Default Income Account), but both Item and Item Group do not have Default Inventory Account.
The closest setting for the inventory account of an Item is at the warehouse level where you can set the Default Account.
This means that the warehouse carries both location and accounting responsibilities. This is okay if all the items in this warehouse will be recorded in the same inventory account (Stock-in-hand), but if you have items with different inventory accounts in the same warehouse (Raw Materials, Finished Products), you have to set ‘artificial’ warehouses for each item type or group.
I would like to suggest that Item and Item Group will have Default Account which will take precedence before Warehouse.
To determine the account for the item in the chart of account, the Item default account will be checked first. If it is not set, the Item Group default account will be checked. If it is not set, then the Warehouse account will be checked (the original set-up).