Q. I’m always customizing my slides even though I use a SlideMaster. Why should I even bother with a SlideMaster?
A. Keep track of the changes you frequently make on your Slides. It may be that you need to create some additional layouts.
For example, I like to have a layout of the Title and Content slide that has no logos or repeating graphics at the bottom, in case I need that space. This avoids a large graphic covering up part of the repeating objects, which makes it look messy. Perhaps you want a second version of all your layouts that have a dark, rather than a light background. Create a second SlideMaster in your presentation (you can have more than one), and reverse the dark text/light background color choices.
Once you have a SlideMaster that meets all these needs, save it as a Custom Theme so you can use it again and again. You can even save a presentation with your Custom Theme as a template, which will already contain your normally repeated slides, such as a “housekeeping” or “thank you” slide.