External Instrument/Channel strip setting for Mono and Stereo signal

Perhaps this is as simple and self-evident as it seems, but I'd like to make sure. When recording a Mono signal (a mono signal from a synth), I have the External Instrument plugin set to a Mono input and the Output Slot in the Channel strip set to Mono Output. I had been using Stereo Output simply because that's the default and only changed it now after noticing it.

Should mono instruments always be recorded/monitored as a Mono Input in External Instrument plugin and Mono in the channel strip Output and, similarly, stereo instruments (some synths with stereo effects) recorded/monitored as Stereo Input in External Instrument plugin and Stereo in the channel strip Output?

Thank you for any advice.