The value of lost load (VOLL) is an essential parameter for power system reliability. It represents the cost of unserved energy during power interruptions. Various studies have estimated this parameter for different countries and more recently, for different interruption characteristics - such as interruption duration, time of interruption and interrupted consumer. However, it is common practice in system operation and the literature to use only one uniform VOLL. Our theoretical analysis shows that using more-detailed VOLL data leads to more cost-effective transmission reliability decisions. Using actual consumer- and time-differentiated VOLL data from Norway, Great Britain and the United States, numerical simulations of short-term power system reliability management indicate a potential operational cost decrease of up to 43% in a five-node network, and between 2% and 18% in a more realistic 118-node network - mainly because of lower preventive redispatch costs in response to lower expected interruption costs. However, changed reliability practices could lead to opposition, if some consumers are disproportionately interrupted and not adequately compensated. Although the first policy measures to collect more detailed and harmonized VOLL data have been taken, future policy should improve transmission-distribution coordination and enable the participation of all consumers in curtailment programs, through smart meters and smart appliances.