It is not necessary, but if your presentation content can be be segmented into shorter sections, that is ideal. For example, a 30 minute talk might have 4-6 sections, each approximately 5-7 minutes. When segmenting, it is best to include an overview of each section to introduce the section, then a summary of the main points of the section before going on to the next section. Use the template below that best suits your talk. PowerPoint Template: Without Sections.
PowerPoint Template: With Sections.