1. A method of operating a facility, comprising: (a) using a computer system that stores an application for determining a plan and a schedule for the operation of a facility; (b) acquiring data from operational activities of the facility; (c) aggregating the acquired data and defining a mathematical model for the aggregated data to be processed; (d) solving the mathematical model and obtaining results, wherein the obtained results determine the plan for the operation of the facility; (e) extracting operational data and combining the operational data with the results obtained by the mathematical model in order to apply flexible time modeling, wherein the flexible time modeling includes: (1) defining a set of targets achievable by the schedule, and (2) analyzing a portion of the schedule covering a plurality of upcoming operational events of the facility in order for the analyzed portion of the schedule as a whole to remain consistent with the results obtained by the mathematical model and with the defined set of achievable targets; (f) disaggregating data that pertains to the analyzed portion of the schedule and determining the schedule according to the disaggregated data; and (g) applying the application to operate the facility according to the determined plan and the determined schedule.