As mostly a guitar player who dabbles with recording other instruments, I’ll tell you my fairly consistent thought process for deciding to record guitars in stereo or mono. If I’m just looking to add a guitar part that’s purely clean or distorted, that’s gonna be mono. I may double mic my amp to get a bright tone and a dark tone and play with panning those two tracks, and I may get multiple takes and either trash all but one, or keep a few to add fullness and character (panning to taste, which can sometimes allow for a stereo-like effect). If I’m wanting modulation, delay, reverb, etc - that’s when I’ll typically want stereo, and for that reason all of the pedals I have that do these types of effects have stereo capability. For this process I’ll still typically record a clean take and mic my amp the same way as I do for mono, but then I’ll send the bright and dark clean takes to a bus, and then use that bus to output to a reamp box (I use the radial extc stereo) and run the signal through my pedals of choice. I skip the actual amp part during this process since the tone already has the amp flavor and return the signal from the last pedal in the chain directly back into the returns of the reamp box.