How do I tell my adviser that group meetings may be too time-consuming in my last year of my PhD? I am finishing up my PhD this year and my adviser has recently recruited two new PhDs to our research group. I am the adviser's first student. Up until this year, we have had consistent individual research meetings weekly. Now, the adviser wants to incorporate weekly group meetings in addition to individual meetings. I think this can benefit some PhDs. However, I don't feel that these weekly group meetings will be particularly valuable to me. This is because I have a clear research agenda that is my top priority right now. I am wrapping up two manuscripts to incorporate into my dissertation, while also applying to jobs and post-docs, to finish my PhD in less than a year. 

I am not discounting the importance of reading new research articles or the importance of collaboration between group members. However, I think the mismatch in PhD progression -- me, a finishing PhD with several first-author manuscripts with multiple collaborators, and the 2 new students, starting to test out and find research ideas -- will take away from my priority, finishing the PhD and wrapping up my thesis while also being a potentially stressful, time sink. This is tied into the fact that my adviser often has poor time management skills, allowing meetings to run for over 3 hours. 

How do I tell my adviser, in a respectful manner, that I cannot attend all of the group meetings? Or, that I think prioritizing my final two manuscripts and dissertation are a more valuable use of my time? 

Thank you for the advice! Let me know if I can clarify anything.
You don't tell him that at all.  You go and contribute as best you can.

Even if the meetings are of no value to you, your presence may be very helpful to your adviser and the newer students. That alone should be sufficient reason to attend. It's not always about what you personally can get out of something. Sometimes it's about what you can contribute.  It's also sometimes about just doing things for people who've done things for you.

If you feel the meetings could be better run, consider what you might do to become a more helpful participant, facilitating discussions and consensus outcomes that don't take 3 hours to get nowhere.  Ask questions that invite others into the discussion, offer your own ideas, propose plans or assignments.  If you were there 3 hours and nothing happened, consider the possibility that may also have been 3 hours when you didn't do much either.