Hi,
Generally business organization sees how scenarios mapped and run business effectively. Mode and method of mapping business scenarios depends on consultant and consulting skill.
Movement type is created based on different business scenarios by copying from standard movement type which need to be mapped where quantity or value updating are characterize to control.In some cases new movemnet type cretaed for account determination process where also new account modifier play vital role. Refer a detailed discussion for a new movement type creation for stock integration/re-integrartion processs:
http://scn.sap.com/thread/3233077
Regards,
Biju K