Bonjour Heroes.
I'm not very familiar with Design Themes because, as Jonathan and Jodi and Julie said, every project is special. However, I'd like to share with you something I do first every time I start a project. For me, with my own way of thinking and doing, it's a great time saver. I create a master slide mask (only one if possible, from an empty master slide) containing everything the slides will share: essential buttons, recurring layers, progress bar, timer, rewards, Menu, instructions, etc... and as many elements as possible. This is my first step. The advantage is obvious: if you need to change 1 thing, it will be the same for all 200 screens in your project.
I'm curious to know if you share this method.
(NB: little graphical effort in this demo. Mostly technical. File.story downloadable from Review)
https://360.articulate.com/review/content/ab005e02-4ed8-4436-bbf2-bd90ea32fb04/review