The author says courses shouldn't have deadlines, but then talks about retention that's measured as of the deadlines. I signed up for the Hinton neural network

The author says courses shouldn't have deadlines, but then talks about retention that's measured as of the deadlines. I signed up for the Hinton neural network class when it was almost over, and completed it well after it ended. Was I "retained"? Did I not count as completing the class? Just because there's deadlines doesn't mean you have to finish it by the deadline.