I've often suggested that the only answer is some sort of brain implant
I know a lot of us think that "dedication time" (or whatever you care to call it) is a ridiculous notion - and it is - but we are usually "shooting the messenger". The person posting here is just trying to implement a crazy requirement from above.
As it's clearly impossible to measure the time a student spends on the course I would just pick some arbitrary metric and stick to it.