Suppose a guest is booked for 4 days, and the day after that is available and the guests ask if they can check out a day later and just offer to pay cash, holding it right in front of me actually. How much of a no-no is it at that point to just say 'yes' to the guest and block the day?
I like saying 'yes' to guests when at all possible, as opposed to forcing him back on the site to process a change.
I'm not personally looking to get out of any fees, I think the fees are very reasonable and I would actually prefer it if the guest did a booking change request. But.. as in the above case, it does happen where it's just easier to just say 'sure, thank you very much.' and be done with it.