A little bit of both is good
Plus with unranked students sometimes gently placing the offending limb into the correct position for them
New students can be easily overwhelmed by too much talk and too much demonstration. They often learn best by being walked through the technique a few times, with adjustment to the feet position and arms as required.
Middle ranking students respond well to short explanations and metaphors.
High ranking students seem to prefer to see the technique demonstrated, with minimal talk to distract them.