With such a wild variance of incoming skill levels, what is the way to make lectures efficient? I know this isn't a new problem but I see it frequently in train

With such a wild variance of incoming skill levels, what is the way to make lectures efficient? I know this isn't a new problem but I see it frequently in training / classes in the industry where things are 10-100x too slow for some people, while others are lost. There is clearly a failure in assigning people to the correct course level (or offering courses at appropriate granularity), but the more scalable thing I see is offline learning where you first check out slides, then check out accompanying documentation / videos, then check google or IRC, and as a last resort you launch the nuclear option of stopping your life for 2-16 hours to sit in a room and learn synchronously. Is anywhere innovating like this?