PowerPoint templates are really useful for business or personal use if you need to create PowerPoint presentations for your organization so often. By learning how to use PowerPoint templates you can reuse later your own slide layouts in PowerPoint and save time while creating your presentations. This is of course a good practice so you can focus on your presentation content and leave the original design and layout intact.
It is easy to use PowerPoint templates, you just need to define the layout including at least a master slide and then additional internal slides and later every time you create a new presentation you can start from your template as a base instead of making the slide design from scratch.