I am dealing with numerous audio files (these are audio books), and have found that using the audio pool is a quicker way to change the properties of many files at once.
Here is my workflow:
Import all audio files into session.
Open the pool. (in the view/attributes pull down menu, make sure tempo and musical mode are selected - you only have to do this once).
Select all files and:
Set to the same tempo, and
enable musical mode on all files.
done.