You can enter and edit text both on the Outline tab or directly on a slide, depending on which is most efficient at any particular time.
Text in placeholders provides consistency across an entire presentation. But you are not limited to using placeholders. You can place text wherever you want it on a slide by using text boxes.
PowerPoint provides assistance by correcting common spelling errors and adjusting the size of text so that it fits optimally on a slide.
You can take advantage of the Find and Replace features to ensure consistent use of terms and fonts throughout a presentation.
Although PowerPoint provides the structure for a presentation so that you can focus on your message, you can manually change the formatting, location, and size of text at any time.