oh yeah... for a verse or chorus on every song, why not check and see how the vocal, bass, kick, etc. are gonna hold up in mono. Granted many stereo guitars, keys, reverbs, etc are not gonna make the journey intact. Also like to flip the phase (of one channel) when in mono just to ear what's left!
I've got a "special" box for for checking mono... 4" speaker 10 watts with a special box attached to help it "fold down" better... sounds pretty amazing.
Done a few records over the years that were actually -in mono- usually something remastered from the 60's, or some ultra hip retro band that wants to recreate that sound.
Records that are mixed in mono are naturally very Solid and Punchy as there are No phase issues... picture that !
Another different check... isolate the Left or Right channel only, just to see what's in there... without the phantom center.
