I think if you havent experienced ice before you can get hung up on watching the leading edge of the wing expecting to see some rim ice forming in text book fashion.
Unfortunately in icing conditions the weater does not know it should behave in accordance with the text book.
My friend operates Kingairs for a living and many years ago I told him I had never seen ice. As it turned out conditions were perfect for icing, and as we entered IMC the sceen went instantly white - not what I had expected at all. You couldnt see a thing out which obviously should not have mattered being on instruments anyway but hell - it was disconcerting at the time.
The point I am seeking to make Flad is your expectation of how icing may manifest itself is not necessarily what actually happens.