Hello,
If a files has recently been change or created on the core server after the preposition job completed WAAS will still compare and run timestamps to the server against the files already preposition to the remote WAE. But the idea about preposition is to provide faster access to remote users accessing core files so if it is a new file that WAAS has to preposition from the scratch users performance might not be as good as with the files already preposition.
So best design depends on how random your server files might change, there are types of jobs you can configure(schedule) depending on your network changes.( if it is something possible to average)
Preposition Jobs:
-All Files (self-explanatory).
- Files Changed Since Last Preposition (compare timestamps of the files on the server against the timestamp from the termination of the last preposition iteration).
-Files Changed Since (specify a time frame in minutes, days, or weeks; files changed within this time frame is collected) should be fetched.
hope that helps!