I surprised there isn't an Access template for this already.

There are a couple. None of them are great. But my goal is to teach people HOW to build it... not to just use something someone else has already built. :)

I would be interested in how you will handle the complexity of all the information needed to be gathered.
I would be very interested in the following as it is something I need to add to one of my biggest apps:

Individuals sign up for a course that will run over several sessions.
The system generates a roster for that course for every day a session is held.
Using a barcode scanner, I would like to take attendance by scanning the barcodes on their IDs as they attend each session.
Then download the scanned IDs from the scanner into Access and assign it to that course-specific session.

I asked ChatGPT for some suggestions. The image below details my favourite 6 suggestions.
I am sure Adam will be a fan of number 6.

Yes Kevin :P.

I'm a fan of 6!

A method to provide feedback based on the training course(s) you took.

I suspect the reason you've got many requests for this is that there are many such products like this out there.  You have covered things like calendar, email and messaging, check registers, and such, and they were probably highly requested too, and that's because they are popular and often used features.  The popularity and ubiquity of those products is why you often get asked to put those features on Access.  No one would ask you to make an Access app for stamp collecting or embroidery organizing.

Below is my slightly OT rambling:

The common belief is that implementing those features on Access would have the added benefit of integrating one's in-house data with the features.  But from my experience, it is often more practical to just use the existing product, and find ways to import/export data between it and your in-house database, instead of creating your own product that looks and works like the existing product.  

For instance, if you like Google Calendar, you could either (a) try to create an Access app that works like Google Calendar, or (b) find ways to import/export data between Google Calendar and Access.  The latter would usually be the easier route (though not without challenges, of course), at least based on my experience.

Of course, I don't object to anyone creating an Access app for employee training (which I imagine would be quite a daunting product to create in Access).  It would be a good way for your students to learn Access, form design, VBA coding, for sure.  But those who have an important business to run, and are concerned with how feasible and practical to do something like this, should consider just using an existing product and find ways to integrate your in-house data with it.