I really don't think they should be burned-in by continuously playing 24/7.
I would let them play at low to moderate levels for 2-4 hrs at a time with different genres, then shut them off for a couple of hrs and repeat. You will eventually hear the difference each time you listen to them to determine the burn-in period, it does seem to vary from headphone to headphone.
You are not describing 'break-in.' You are describing normal headphone use.
Are there any research articles or experimental studies people can link me to re: burn in?
I would think that a diaphragm moving constantly for many consecutive hours could very well change the sound characteristics; then again, when I read anecdotal reports about the effects, different people seem to claim completely opposite effects: more treble in some cases, less treble in others.
I don't notice any systematic pattern to these anecdotal claims, which leads me to suspect that it's a placebo effect.