Maximum Length for Multirack Session

Audition should be able to handle this, but I can't really help you because there are way too many variables that will affect the outcome - I'd need to know a lot more about the way you are working. As often happens, you've been poorly advised by the Adobe helpdesk (who don't actually use the software and do it all from crib-sheets), and now appear to have been prejudiced by a ProTools user. I can't do anything about that - it's your choice as to whether you believe them or not.

What I will say though is that in order to do what you want, you have to work smart, and utilise the software's strengths and not its weaknesses. Unfortunately one of the weaknesses is that it doesn't like having huge sessions just dumped into it wholesale with little regard to the consequences. What works far better is just exporting what you need to work on externally, and then round-tripping it. And it's the same with NR - don't try doing it on the fly when you've dumped 16 tracks across (most of which you probably didn't need to), but instead clean up noisy tracks before you place them in the edit. In other words, do some pre-processing. It's often better, especially with programs like RX, to use them as standalones. You have to bear in mind that if you use RX as a plugin, then all your signals are being handshaken twice - once into Audition, and then from there into RX using a very similar process. And you're wondering why it slows down and sometimes doesn't work on the way back?

Unfortunately it's true that Audition is best used as a 'sweetening' tool in a video mix, and that as far as the heavy lifting for the edit is concerned, do it in Premiere. Once you've figured out the strengths and weaknesses though, it's fine - if used appropriately.

I found out from Reddit that ProTools is the better application for editing any session over 16 tracks, and over 35 minutes in length. Audition just can't handle the time and the amount of tracks yet. Hopefully they will be able to soon. But for now, I advise anyone with the same issue to use ProTools instead. Thank you.