All the rendering is done on the mixer channels. So whatever that channel is, mono/stereo/5.1. That will be the sum.
The export is in need of a update.
I have 32 outputs. Setup as 26 mono outputs and 16 stereo. This gives me alot of flexibility when I do export. If you only have that master output. Export is a pita.
Also as mentioned the pan of a mono track will have impact when you use the option to mono downmix your master out. Depending on your pan law, If you pan mono and send to stereo, it wont turn back to its original value on a mono downmix of that stereo track. Only “perfect room” -6db pan law, will stay flat. But there is a simple solution of bypassing the panner. That will fix that issue.
At the moment the Direct routing is a bit so so… You cant simply just setup a extra mono output to mono sum a mono channel. As the channel dosent update pan to the extra slots and only first slot. So you dont get the mono to mono routing when you swap output, wich will move the pan to the channel on the mixer, so your level stays correct, you get mono-stereo-mono. It is silly, but workable when you know about it (bypass panner). Also this is post fader. You might not want that for a “track freeze”.
I like using oldstyle method. So if you setup a extra mono output in your project audio connections and send a signal to that channel, using channel sends. It will go mono to mono, so your levels will stay correct. You can choose pre/post fader level. Just export that mono output, and like magic you have a perfect export of the mono channel. And you dont have to do the extra steps of bypassing pan and messing with your fader, to get correct values. And now you have a solution ready to go, when ever you need it. Less steps, quicker workflow.
Sorry if this is a bit technical. And overload of information. But I have to deal with exports all the time. I would be in a mess if I dident have all my outputs. I can export whole sessions where mono tracks stay mono, stereo stay stereo, choose pre/post fader, pre/post/bypass pan and grab me some coffee while the daw do the work.
I cant imagine how much of a pita it must be working export with only master output. Export is in need of a update. Make it more flexible for the users with less outputs.
Have basic things like
select bypass pan/fader on tracks,
select mono/stereo export on tracks,
bypass automation on tracks,
bypass plugins on tracks…
And all options should be made as options for induvidual tracks in a multi batch export.
Anyways I hope this will give some pointers, to improve on your export 