I don't cover my feed dogs at all! Guess we all do it our own way. Leah Day had a video out about FMQ-ing with the feed dogs up..that's where I learned it. I find that with the feed dogs uncovered, they move the fabric when the hopping foot goes down..you can get into a rhythm that way and the stitches are much more consistent. Leaving them up and uncovered still allows you to move the quilt sandwich freely, as the hopping foot doesn't pin the fabric down like a regular foot.