So do people usually use CTA2 just for long scenes... because adding music needs to blend from one scene to the next... so in my circumstances would you suggest I make it all silent in CTA2 and add sound, music and voice-over in another software program?
For the best control over the sound mixing one would have all the sounds in the movie editor.
Of course, any music or voice-over spanning scenes would have to be in the movie editor.
What you do need to have in your project is any actor(s) speech so that the actors mouth can sync to the speech.
But that does not mean that you can't also have the same speech in the movie editor for final mixing control and then just mute the original.
You would put sounds and sound effects in your project so that you can perfect any timing of the actors and action to the sound as needed.
You can leave the sounds in your clip and adjust in the movie editor as long as the various sounds do not overlap. Otherwise use the movie editor to mix in the sounds.
It comes down to what works best for you and your production path.
Get my Plugin Manager and TaskNotes plugins for iClone.
Check out EZColors for CTA/CA. The easy way to change Render Styled (RS) colors
See my CTA Tutorials on the YouTube channel CTAStepByStep