I have a midarm sitdown and I keep mine on needle down all the time -- mostly because my quilt sandwich isn't on a frame and much more likely to move if the needle isn't down. On a regular long arm, I would do the same in case I accidentally bumped it.
I also have a speed setting and pretty much always leave it on the same speed. I don't have a regulator, so it helps me stay a bit more consistent in how I push the pedal vs how I move the fabric