[DowagerDave]

The timing is super important. Writing on a chalk/whiteboard or overhead takes time, which is required to absorb the content. Hitting the right timing and cues with this approach seems like it would take a lot of practice, which isn't a deal breaker, though I believe the 2 biggest problems with most presentations is too much/too fast content, and not enough practice and this approach might make those both harder, not easier.