I never cut a thread off a quilt top that hasn't been buried first. Takes more time but that way I know I'm not pulling or cutting something important. I use a big eye needle so it's easy to thread. For ends of stitching when I'm quilting I pull the top thread through, tie it with the bobbin thread and bury them both by threading them on a needle and running them through the batting layer. Makes for a neat stop and start point and everything is secure. Good thing to do while taking a break from the machine or watching TV.