A few tips below may help:
1. In the book One to One by Lucy Calkins and Amanda Hartman, clarity surfaces as a key to saving time. We must be clear during our mini lessons so that students can be clear about what they are doing as writers. Students must be clear about how to discuss their own writing processes. The best place to begin this work is in the primary grades, and this book has a wealth of practical ideas and excerpts of “real live” conferences with students.
2. When working with intermediate students, one suggestion I can share is to read work in advance of meeting with students. When I read the work in advance, I can learn so much about the writer. I still need to listen to students about their intentions as the conference begins, but reading ahead of time helps me think of ways to support writers. Especially when pieces are quite lengthy or complex, it helps me to read work in preparation for a conference.
3. Ask students to let you know exactly how you can help them. One reason some conferences may take more time than needed is the student may not need a conference at that time. So, put it back in the hands of the student, and say: “If you want to meet with me, write me a quick note about how I can support you as a writer during a conference. Do you need help with ideas? Do you need help because you are stuck in the middle of a piece and you don’t know how to continue? If you let me know how I can help you, and precisely which part of your piece you need help with, we can both save some time.”