737NG procedure is to deice with flaps up and then cycle the flaps from Up to 40 and back to Up before taxi to verify freedom of movement (assuming they're not covered with snow and remote de-icing will be conducted) and taxi to the holding point with the flaps up.
Stops contamination being thrown up by the wheels into the flaps, slats and the mechanism which could then lead to an interesting takeoff when retracting them, and it helps with the holdover.
Also taxi in with flaps extended if a contaminated runway and check for contamination in the flaps on arrival before retracting them.