Maybe I didn’t get what you have stated, but I get this, here, when recording an acoustic guitar with a mono source (a condenser mic - all inserts and sends having been disabled) in a stereo track, something I often do :
For some time, it had been as @Martin.Jirsak said. If your Audio Connections Input bus did not agree with what was actually connected to the interface, a mono source (that hadn’t been declared as a Mono Input bus over at Audio Connections) would be recorded on the Left (or Right) side of a track when the Stereo Input Bus was selected.
But (and again Buildela effect for me), at some point we were given the option to select a Hardware Bus as an audio track’s input. And then a mono source will happily record itself on a stereo track, centered and all.
(By the way, I’m mostly using stereo tracks these days, even for mono material. In absense of a quick mono/stereo track switch, I prefer to start with a stereo track so that on a whim I can try a reverb or a chorus as an insert effect and have it sound much better. If I want to make it mono later on, I can always create a mono bus, or narrow the pan down to a point. But to “stereo-fy” a mono track, I would always need to create a stereo bus and copy over the inserts.)
No, as far as I can see there is no benefit.
In case you want to make your signal mono you can switch the panner to stereo combined and narrow it to a C C setting
If you want to use a plugin that is a dedicated mono plugin (e.g. some compressor emulations), use the same technique but set it to L L or R R instead. You can assign any necessary routing in the Routing tab of the Inserts section in Channel Settings:
Good to know.
I checked on supervision is there was any difference comparing the same mono event on a stereo channel and on a mono channel, but it seems to be the same, so I’ll probably keep the tracks that way then!