Really?
Your not talking about the odd cell here and there, your saying they will turn a "patch" or frame of drone cells into worker cells without prompting in a reasonably short time?
I have not been beekeeping that long, so I have not seen them "repair" a patch of drone cells. Does it take awhile?
Do you have to do anything to get them to go back to worker size cells? My solution for this "problem" has been to put in new foundation or scrape the wax, depending on the foundation used.
Very interested to hear your observations!!!
RKR