I cut my threads as I go. This was drilled into me in Home Economics years ago. I can't stand the look of dangling threads. It only takes a second!
If my teacher saw a thread hanging we would immediately go down a grade. Last year when my granddaughter had sewing I was telling her the same thing. She got in the habit of cutting her threads and the teacher was so impressed she gave her extra credit.
A friend of mine just went to a quilt show and there were some quilts with hanging threads. I can't believe they would even allow one to be shown that way.