Actually, in that point, Mr. Duran has a point, although not completely accurate.
Deicing and anti-icing fluid is a somewhat viscose fluid that also decreases the effectiveness of the supercritical wing, although in a FAR LESS way than ice/snow contamination. Especially Type2 and 4 are quite viscose, but nowadays less used in Western Europe it seems.
What I would like to see is a recurrent yearly class on winter-ops, not just a meager CBT session of an hour at home, but a real classroom style day-long briefing where all aspects of winter-ops. are being repeated and where there is room for discussion.
In my opinion, at least as necessary as yearly CRM courses.