Longer ones lose our interest. Indiana They are of minimal value, since they tend to reinforce a belief or pose a new one. Sometimes in a busy schedule, a short session is all that I can handle. Learning little bits at a time is not overwhelming. They include an opportunity for hands-on activities plus time for questions.
Longer sessions tend to oversaturate the participants.
If it is an introduction to a new topic, it is not valuable. The answer to this question depends on who is teaching. Really, something is wrong when people who do not currently teach in our classrooms come around telling us how it should be done. If they can do it so well, then they should do it and not tell it. They are actually using what they are teaching.