I trim while sewing ... and do a trimming and cleaning of the back before sandwiching.
I asked my LA'r one time if I was doing more work than necessary. She did say that mine were some of her "cleanest" tops she receives. It's kind of a yes/no situation.
Some reasons why ... the threads can show thru, if you have lights/whites in the quilt top. They can sometimes bunch up, and cause problems when quilting.
Why not ... more safety with longer threads left. Who sees it once it's sandwiched.
For the better part, I think it's our Type A-ness (as in A-nality) coming thru ... and we need to do it, to keep ourselves happy!!
