As said above planning phase is the most important phase of a project as every other phase of a project is dependent upon by this phase. Planning involves a lot factors before putting into practice this involves checking on a lot of things that involves availability of employees and the estimating the time required for a particular task with the available employees. This is important to consider so that you do not have to go back to make any changes to the planning phase as this would have a bad impact on the project and the people associated with the project. However, for a worst case scenario a backup plan and substitutes should be kept in mind while going ahead with the planning phase.