Persoanlly, I believe that at training stage, students should be given as much time as possible. This gives them additional time to prepare and self brief and make the most of the lesson, which they are paying for after all.
I don't just mean time for the formal planning, eg W&B, flight plans, nav calcs etc., but time to prepare mentally for the flight and consider what was done wrong last time and how can that be improved next time etc.
Yes, in the real world time is tight but at that stage experience helps and we all know we are quicker when we do the same thing several times a day/week.
When I go for light aircraft flight these days, even local currency for an hour or so, I always brief myself on what I want to achieve and improve on and set myself goals. Then afterwards I critically review how I have done and set further goals for next time.