I suspect that we are missing two important, but related, points ...
(a) standardisation. Presentations using a prepared format (of whatever sort) to cover the basics mean that students get the required material covered in some sort of standardised manner - so that we don't miss bits with the invariable digressions which occur - I have a bad habit of digressing and getting onto more interesting bits and pieces, you see. How slick you might go is then a matter of cost, time, and interest.
(b) further discussion or explanation is going to vary according to the student, student's interest and background, etc. This phase is better handled in a tutorial fashion using the more traditional aids.