I have to toss in my 2 cents worth. I tried FMQ for the first time this year on a small lap quilt. Being frugal, I decided to use up some batting that I had bought in a box of auction stuff. Not being knowledgable about it, I decided I better quilt it close because the batting looked like it would come apart between the front and back if I did not do that.(Looked like some kind of cotton.) I learned that it takes a TON of thread to do close FMQ. Then after I had finished it, it was really stiff so I tossed it in the washer. It did soften up a bit and I suspect with a few more washings, it will get a little more flexible. If I do try FMQ again, I will use Warm & Natural and probably try to keep the lines about 4-5 inches apart. Still very much a beginner though and I need lots more practice. But a very good question and as usual, some wonderful answers.