SESX Duration Modification - Shortening and Lengthening

I understand this question. For example, if you are working on a 30-second piece, such as a radio commercial, it can be prohibitive and a pain if your .sesx (session) file is super long, say 5-minutes, or even 30-minutes.  This happens a lot when you important a long file, let's say 30-minutes, into your session, but you only take 5-minutes of the file. Then, your session is 25-minutes longer than it needs to be.This makes zooming and cutting a real pain. So, is it possible to cut the length of a SESSION? Not export the multi track to a mixdown of the proper length. 

I'm not totally clear on exactly what you want to do.

If it's just getting rid of extra stuff at the beginning and end of your session, you can just highlight exactly the section you want then do the usual File/Export/Multitrack Mixdoen and select the "Time selection only" option.  This is also useful if Audition has added some extra silence at the end of your session (which it will do if any of you effects like a reverb will hand over the end of the work area.

If you want to actually change the length of the actual sound, this can be done in the Effects/Time and Pitch menu.  It's likely easier to mix down your project then change the duration of the single mixdown.