I have course development repository in former VS TeamServices. Now I plan to have separate ones for each course, this is a faculty only repo. I create a startup repository that becomes the one for the students to clone.
Reference: Commit is the new save
I ask my students to commit every time they make a change.
One liners, starting with a what (add, create, modify, delete, etc) as atomic as possible.
They do get it once it is project time and face real issues.
As often as they check their phone.
For individual assignments as often as they can. For a team project, always. As long as they are pushing to a working branch. For master or solution branch, after testing and peer-reviewed, must use PR in this case.