It is explained in the documentation.
'Load as Saved' does NOT ensure you have the latest! It means you will load the assembly as it was last saved, including an older revision of a part that has changed since the assembly was last saved, assuming you are using part versioning and not connected to a PLM system.
Part versioning is a must to setup and use if you want to be able to load the latest components of any assembly. They work along with the load option 'Load Latest' and search paths. One note about search paths is that NX will load the first instance of a component it finds rthat matches the search criteria, even if there is a newer version in a later folder.
For engineering, we put the WIP folders at the top of the search path. For manufacturing, we put the released foldrs at the top.
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