All the role change depending on the situation.
For example, a Weapons officer needs to be heard when he’s loading something, so that the Engineering can boost tubes, but other times probably has nothing important to say, regarding the station itself.
I think that the basis for all of this is much simpler:
- if an officer of higher rank is speaking, shut up unless you have something important to say (if you think that it’s important, you’ll be corrected if it’s not);
- if you’re talking and the higher ranked officer starts talking at the same time, shut up.
If we all follow this, the pure experience you amass while you reach Lt.Jr. will let you know when you can or should speak. There are a some Cadets and Ensigns that have not yet learned this important lesson.