My wish for all of my students is that they establish their own Best standard in writing--and then strive to surpass it with each new project. When a student asks me, "Is this good?," I often ask, "What do YOU think?" The student either shrugs and says, "I don't know," or nods proudly and awaits my critique. To those who shrug, I usually say, "Can you add more details? More D.A.D. elements? Can you find repetitive words or off-topic ideas to cut out?" Those questions make most uncertain writers say something like, "Oh yeah, okay...," and return to their seats to revise.
These two kinds of responses to "What do YOU think?" indicate to me that what students need most in establishing their strongest writing skills is to first establish themselves as credible critics of writing. The writing workshop format allows students to learn self-editing skills by starting with editing the work of their classmates and published authors. Public critique sessions following the sharing of writing pieces thus lay the foundation for writers to learn evaluation techniques that will eventually transfer to their self-evaluation skills. Now, no one can be completely objective about his/her own writing (I have a critique partner to keep me "objective"), but learning to critique certainly enables us to accept and integrate suggested revisions without destructive defensive posturing. In short, the workshop format of writing instruction stresses writing as a communication process, not the fulfillment of a teacher's assignment.
So when students don't participate in the discussions of their fellow students' work, they overlook the application of the discussion to their own work. I have had parents say to me, "My child is bored having to listen to the other kids' pieces and comment on them. Can't we have a private lesson instead?" Sometimes I do make time to give a private lesson, if the student truly works best in a one-to-one session, or is disruptive to a group due to his/her own insecurity; but I strongly feel that to become the best writer one can be, nothing beats a workshop for facilitating growth.