I alluded to this in another thread in this forum. Recording a lecture, of just a monologuist in front of a camera, will take up at least the time it takes to deliver the lecture. But preparation of the set, like lighting, camera placement and focus, takes enough time on its own, plus any post-production, like editing false starts or lost tracks. and if there were enhancements, like cuts to close ups of demos, there is even more time invested.
And wisely. The students need to see something that works right and is easy on the eyes or they are… >>>