The checking or studying part of a project is an iterative process that includes measuring progress and performance at task, activity and project levels and includes reporting of achievements.
The desired output of this stage is therefore checking that the schedule of tasks and the activities are on time, to the right quality and right cost level to the satisfaction of relevant stakeholders. For instance, a task may be carried out to the satisfaction of the project team members but the end user may not be entirely satisfied and therefore the earlier you know about this potential problem, the less cost it will be to rectify and the sooner it can be fixed.
We have already mentioned milestones and checkpoints are there to celebrate achievement and check progress. If progress is being stalled then interventions can take place to get the project back on track, so milestone events and checkpoints are essential along the way to achieving your project goal.
Record any observed issues in your issue log so that this can be discussed with the project team. If results are positive, the project can continue in the same way. If results are not positive however, consult the project manager or sponsor about potential corrective action. This is an iterative process that should continue until you have achieved full implementation of the project and achieved the project goal.