If I may share what I personally do..
Me and my cleaning team only wash the cover and schedule to wash the comforter itself once in a month for a couple of reasons :
1. We have a thick cover and slightly water repellant hence, we did not find the need to wash the comforter itself so often.
2. I am trying myself to be more environmental friendly as hotels and acommodation services do so many damage to the environment with unecessary water usage for washing the laundry too often. I even have a rule of changing the linen and towels once every 3 days for long staying guests as I am very sure that normal people will not change their towels every day dont they? So I kindly notice them of my rule before their bookings confirmed.
But I do help them change when needed : )