I avoid them. I did a series of shops (at their request), and after submitting the report they came back with tons of questions that were nowhere in the guidelines, and we're not the types of questions usually asked on a shop. As I did my best to answer--I was surprised how much my notes helped me remember--they said it wasn't enough and wanted more. By then I had written so much it could have been a dissertation! When they accused me of being stupid for not generating enough words for them, I collected my pay and put them on my 10 foot pole list.
It could be different now, as that was years ago and there might have been managerial changes. YMMV.