IME early departure fees are a fixed amount (perhaps $25-$100 in the USA) and apply only if you shorten your stay after check in. I would expect most hotels to waive the fee if you announce your intention to leave early in accordance with the cancellation deadline (such as T-72) for your rate plan with respect to the day you are leaving. OTOH, if you're leaving early due to a fault of the hotel. such as no hot water, there should be no fee (an often a customer service apology gesture, often in the form of points to cover a night at the property, depending on the severity of the issue).