Over the years, the maintenance of information necessary for control systems – information bases – has been a thorny issue being raised by both researchers’ and practitioners’ communities. These days, information bases of modern industrial computerized control systems are forced to be modified too often, so the process of maintenance is highly iterative and should be more accurately referred to as updating. The matter is an exceptionally high rate of arriving jobs that create real flows. In this situation, characteristics of job flows are becoming extremely important for designing and applying suitable updating tools and estimating timing budgets for updating. However, no appropriate law or model for job flow prediction is presently available. The article advises to take into account particular situations, or situational factors, to explain and forecast job flows. To advocate this idea, a brief review of situational factors affecting information systems is presented, and the most critical ones for information base updating are selected. As an example of putting the idea into practice, the results of the investigation of nuclear power plant upper-level control system information bases are presented, and the influence of situational factors is demonstrated.