Purpose of Project work scheduling

Purpose of a schedule is to encourage everyone to see her efforts as part of a whole, and to invest in making her pieces work with the others. Until there is a draft schedule suggesting specific dates and times for when things have to be ready, it’s unlikely that connections and dependencies will be noticed. Without a schedule, everyone will focus on her own tasks and not think about how her work will impact others.

The schedule provides means for identifying and highlighting critical work package and tasks on the project.
It simplifies the project plan: the bar chart type work schedule provides a simplified version of the work plan, which can easily be understood by all concerned with planning, coordination, execution and control of the project.

Reveal developing problems early so that action can be taken to deal with them.
Identify areas where other projects should be managed differently.

It optimize the resource employed: a work schedule is based on the most economical employment of the resource of men, materials and machinery. It smoothens abrupt changes which may occur from time to time . resource optimization  is achieved by a systematic utilization of the flats of non critical activities. Unless otherwise constrained, a project is  schedule using either the optimum or the available pattern of resource.

It validates the time objectives:  a work schedule shows the planned sequence of activities, date-wise. While putting the work plan on a calendar basis, it takes into account reduced efficiency of resources to adverse climate conditions and other factors. It verifies the deadlines imposed for completion of the project and achievement of the milestones.

It evaluates the implications of scheduling constraints: a work schedule brings out the implications of constraints, and enables preparation of a plan of work within the framework of these constraints.
Improve project performance together with the management of project.
It forecasts the input resource, and predicts the output: a work schedule enables the forecasting of resource and also indicates the pattern of resource consumption. The time schedule of work forms the basis for predicting the resource requirement as well as the financial state of the project in terms of investment, expenditure, out put and income.

Mastering Project Management
 By Scott Berkun Project Planning,Scheduling,& Control: A By Lewis                                                    Construction project management: planning, scheduling and controlling