Hi Amith
We use shipment process to have clear distinction of cost and freight occurrence at each leg...For example if your shipment includes involvement of rail, road , air and sea.For each mode you have different vendor and you want to capture cost for each mode as well as you want to charge based on this cost to customer then shipment process will be the best bet but if you want to charge fixed freight charges to a customer then directly determine freight condition KF00 in a sales order.
Usually companies adopt shipment process to analyze and reduce cost involved in shipment by optimizing routes and deliveries of multiple customer.They plan to deliver different orders in one shipment and load orders in a truck based On LIFO..I.e. last in first out principle.
Let us know your thoughts or if you have any doubts.
Thanks
Amit Gupta