It's very common for companies to place a purchase order for every sales order line, and Odoo handles this well. The problem is that users have to remember to select the "Buy" and "Make to Order" routes when creating products.
Because the list of routes is not fixed these are not standard fields that can be defaulted in the normal way. It is possible to correct the data using download and upload, but that's not a great solution because users may create a new product and then place (and confirm) a sale order immediately.
I tried "Automated Actions" but without any success. Any suggestions? [Odoo11 Enterprise]
I can't comment on Pinakin's suggestion, but it works!! I hadn't seen this option because the user needs to be authorized to "Manage Push and Pull inventory flows".