How to conduct an effective regular group meeting? My research group has regular group meeting but I usually think it is not effective. In particular the research area of the group is very diverse, every time I just listen on something I cannot understand and have totally no interest on it, and I believe other members think the same way as I do when I am presenting. While it is a good way to expose to something new, and know other group members what they are doing, this is not effective for my own research. I know group meeting has its point (What is the purpose of the weekly research meetings that advisers often have with their research group?), but how can it be conducted in a more effective way?

As a supervisor:


How frequent should a regular group meeting be? It depends on the field, and I hear something like daily to three months.
When should a regular group meeting be? I know some groups insist on Monday morning, some groups choose Friday evening which is terrible.
How long should a group meeting be?
What level of detail should a supervisor comment to one's work? From every experimental concepts, to a vague conceptual suggestion?


As a student:


What should a student prepare before a group meeting to have an effective meeting? To present every problem he/she faces, or just some significant results (if there is)?
Should a student question other's member work? Sometimes it may be constructive, but it can also be an interruption.


If you are a faculty, how do you conduct your group meeting? As a research student, what can you suggest for an effective group meeting? An effective group meeting can greatly help on one's research work, otherwise it is just a drain of energy, time and motivation.
You have a lot of questions interspersed within your question, but it sounds like the main issue is


  the research area of the group is very diverse, every time I just listen on something I cannot understand and have totally no interest on it, and I believe other members think the same way as I do when I am presenting.


I have had the same problem in the past.  I'm a professor who works in a variety of related subfields, some very theoretical and some fairly applied.  Most of my students and postdocs have been focused exclusively on either something theoretical or something applied, and their backgrounds range from computer science to mathematics to electrical engineering, so there is often a disconnect when they try to communicate what they are doing.  Here is my advice.

For students:


Try to broaden your focus and interests.  It is natural that you have a very narrow research focus as a grad student, but if you want to get and keep a job afterward you'll almost certainly need to broaden your focus.  I find that in general the best researchers almost always have broad interests (though they are able to focus their energy narrowly when needed).  Group meetings are an opportunity to become acquainted with topics that are on the horizon of your current knowledge.
Use group meetings as an opportunity to improve your communication skills.  Teaching non-experts about your work is a critical skill in any research career.  Other students in the group do not know nearly as much as you about your research topic, but that doesn't mean that you cannot make it interesting and accessible to them.  Often this means leaving out the "details" and explaining just the essence of a problem.  Trust me, some day soon you will need to make your work interesting and intelligible to people who are much further removed from your specialty.


For advisors:


Help students to present their work in a way that the others can understand.  Often this means prompting the student, especially at the beginning of a presentation, to add important assumptions, motivation, or background.  The student has started to take these things for granted, but without them any non-expert is quickly lost.
Don't let the conversation drift too far into a very specialized discussion.  If you and the student are the only ones who have any idea of what is being discussed, it's probably time to say "let's discuss this further after the meeting".
Use meetings for skills development.  This was already mentioned in this related answer.  Instead of focusing exclusively on research, group meetings can also include discussions of things like:


How to write papers
How to read papers
How to search the literature
How to manage a bibliography
How to give good presentations
How to write a proposal
How to keep a lab notebook
How to keep up with newly published research
How to stay organized and be productive
How to referee a paper
Software tools for all of the above, and for research



These topics are useful and interesting to anyone involved in research.

Answers to other parts of the question


I hold group meetings once a week, and they last 1-2 hours
Students are strongly encouraged to question and comment on each other's work
We meet at lunch time, and there is food.  That doesn't sound important, but I think it is.
I try to save very detailed comments for my one-on-one meetings with students.  Otherwise, the group meeting can devolve into a conversation between the advisor and just one student.