It may even be prudent to do a static run-up after landing to shed ice before shutting the engines down. It can save you the bother of having to put engine covers on or bringing out the hot air for fan blade de-icing. Though, in my experience it's hard to shed the ice completely off the inner part of the blades.
I am still curious as to how 'aerodynamic' the fan blades are and how much they are just big paddles shuffling air backwards. The amount of ice 'acceptable' during walk around will always be a subjective assessment.