Hi @RobertGibson,
This is an interesting question, and as you probably guessed, I don't think there will be one universal answer.
The first thing I'd consider is whether everything in the course is designed around modules or not. If the entire course is modular, my initial inclination would be to include info about the next/previous buttons in something like an "intro" module or announcement when the course begins. If the course is a mix of modules and things not in a module, you could put the info on a page at the beginning of each module. I don't think I'd include it on every page as that would get repetitive, and some things in the module might not have a uniform look (I'm thinking specifically about a discussion or a file, but there would be others too). Does this help you at all?
I notice you also said "orientation course" as an option, and I'm not sure if you meant a separate student orientation course or a orientation module within the course. As least at my institution, teachers have a lot of freedom in the way their courses are designed. Some will use modules, some will not. For that reason, when we have a little Canvas talk as part of general orientation for incoming freshman, we don't get into course specifics too much. We'll give info about logging in, setting up notifications, the dashboard, reminding students to check courses often, communicate with their teachers, and how to contact support. That's about all we do (though it's still a lot in a short time).
I hope some of the info I provided here was helpful, but please do let us know. Others may chime in with their own opinions and practices around this too.
-Chris