Configuration of invoice_method and shipment_method at customer level.
The sale module allows to define a value for invoice_method and shipment_method at the sales configuration level but it is not possible to define a value at the customer level for these 2 methods.
It would be interesting to add the configuration at the creation of a customer to define the default behavior of the customer when creating a sale. The 2 methods must remain modifiable at the level of the sale.