Before I started university I already worked as a web and iPhone developer.
At university I failed some courses so I needed the points for three additional courses at the end of my studies.
Durin summer vacation I found online courses from a different university which would count towards my own points. So I registered for three of them. Web development, iPhone development and open source development.
When the courses started I waited until the weekend and then did all assignments and tests for all 3 courses during a single day. I started in the morning on Sunday at 10 am and sent in my last test at 11pm. So instead of half a year (one course takes normally half of a semester and I had three), I did it in one day.
Were all the tests available at the same time? Usually there are different times for submitting tests and also for assignments. I've never taken a course where you can just submit them whenever you want. For assignments, maybe, possibly with some penalty. But never for tests.
Did it once back in the day, I just asked the teacher if it was ok to send everything at once, but that was in paper form though so they just sent everything in a package
Yeah it was a fully online thing, they also had like a forum where you could talk to the other people taking the course but they just gave everything on day one so you could do it at the pace you wanted.
Most people don't realize you can actually get free credit for courses if you're already familiar with the material by taking some exams. It should probably be more obvious these days with how popular AP classes are but a lot of students don't realize that's an option.
The institution will usually have information about how their supplementary exams work. It will usually be on their curriculum guidelines page of their website.