Re-plastering necessary for cob/Adobe if it is not exposed to the elements?

I have heard that there is more or less annual maintenance required for cob and Adobe; specifically they need to be replastered every year.

Is this true no matter what--like if I build a cob structure that is entirely inside the envelope of my house? Or is it only based on the idea that the outside elements, or differentials between outside and inside conditions, degrade the plaster of cob/Adobe exterior walls (both on their exterior and interior surfaces) thus requiring the constant repair?

Hi Ned,
I haven’t heard of that strict maintenance routine. If exposed to rain cob and adobe might need regular re plastering. Otherwise I can’t imagine why that would be necessary. And of course it would be much wiser to protect the cob from rain than to be constantly repairing the damage.
I live close to a 700 year old castle ruin made of rammed earth. I don’t think anyone re plastered  it since 1492. And the wall and tower still stand.

Maybe the annual maintenance is wise if unprotected walls are lashed by rains.  What is more wise: always follow the "good hat and boots" mantra