It's interesting you brought up this topic, because I too have often thought about what it would be like to wear my diapers when I am on my period. I have never worn throughout the span of time in which my period lasts. For me I feel as though that would be uncomfortable. I have worn towards the end of my period when I am much lighter and I have done okay in that respect. But because I am often heavy in my flow, I often find myself changing out my feminine products quite often and I feel as though if I wore my diapers throughout the week that my period lasts, I would be changing to frequently before I got complete use out of my diapers and I would then be wasting them. So for me, I prefer not to wear my diapers while I am on my period, unless it is towards the end when I am lighter or as you said, should I need them because I do not have enough supplies I need. And who says diapers can't be for more than just potty purposes
Good question though. This is one that I have often been thinking about lately.