They would be valuable if followed up with other continuing or related sessions. Short sessions are easier to schedule and are teacher-friendly but are not heavy enough in content. I prefer more in-depth sessions. Short sessions are usually generalized and more of an overview. It depends on the presenter, but usually the shorter the better.
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.