The C-5 has no LE anti-ice on the wings or tail, only engine anti-ice. I've flown many times in what should have been icing conditions and made only slightest amount of ice. I flew the Citation in the NE US for 4 years and 2800 hours and rarely used the boots.
Jets seem to have less problems with airframe ice than turboprops/piston aircraft. I think ram rise helps, abundance of power helps--fast climbs and descents thru likeliest icing conditions. Flew Aztecs and Barons in the same areas and nearly got "shotdown" in ice several times--I respect it from experience.
On the ground, different story--clean wing or off to hotel.
GF