Sometimes, even professional practices can view their available staff time as a fixed cost, particularly if revenue is volatile and unpredictable. In these sectors, key indicators tend to revolve around 'occupancy' measures as a rule of thumb to estimate profitability levels. Calculating a breakeven number of passengers is crucial to these businesses. These costs won't change much, whether the asset is fully-utilised, or sits around idle. The rest of the room rental goes to cover the fixed cost of having the room available for usage in the first place.
Similar examples apply in the other sectors.
Unless there is a stream of people paying to use the facility, the fixed costs ultimately kill the business, since there is no revenue to cover them. Each extra dollar of revenue provides a relatively high 'gross profit margin' or 'variable cost margin' to offset the fixed costs, based on the 'normal' price of the service. So a key business aim is to crank up the extra revenue - this can be done through different promotions for the business. So all the tips about 'measuring the effectiveness of advertising programmes' still apply in this type of business. Or a business owner can learn from some of the big players - the airlines or the large hotel chains, for example, spend plenty of effort structuring special deals and pricing approaches etc that target or appeal to various parts of their market.