I used to iron for a living while my children were in school. I would always sprinkle them and put in plastic bag. I put them in the freezer made for much easier ironing. I still iron but I don't sprinkle them now.
I also use that idea of batting or I use felt and take a piece of fabric just a shade smaller ane sew down center to put in my take along sewing. That way I dont leave unwanted thread on there carpet.