I do not know if this particular 51-day limitation was intentional or no

I highly doubt it was intentional. Boeing's already had to issue an AD for similar behavior on the 787:

https://www.engadget.com/2015-05-01-boeing-787-dreamliner-so...

If they knew about it there'd be no need for an AD. Boeing tried to become the aviation equivalent of a fabless chip designer with the 787 and it didn't go well at all. Turns out they had little-to-no experience managing external development and manufacturing teams. I don't know anything about the 51-day bug, but the 248-day bug caused critical failures that you really wouldn't want happening in flight.