To be as impactful as possible, teacher training should be as realistic as possible. This can be difficult in a school situation, as we don't have live students in teacher meetings with which to practice methods or approaches. That would be an interesting exercise, but probably not often practical.
Schools can use role-plays and analysis of video, or, even better, live lessons with teachers as the 'class' to make the situations more realistic.
Having teachers engage in teaching, even in a short format, will require then to think carefully through the steps of the 'lesson', and the following time for critique and analysis gives valuable feedback to both the teacher and the participants and observers.