Interesting fact you're presenting about your own testing. Perhaps the reason why the pilots of Russian Caravan that went down talked about everything about no ice to severe ice.
The feature 'similar threads' was really helpful and I found some pretty good info in those. This one for instance:
http://www.tsb.gc.ca/en/media/communiques/air/2006/comm_a05c0187.asp
Regarding the operation of de-ice boots. I have no experience myself but I try to recall from the ASP class. If I am not mistaking de-ice boots shall not be operated at once ice is building up on the wing but after a layer (how thick?) of ice has built up - otherwise the ice will not crack and fall off. I don't quite understand this to be honest, if the layer isn't deep enough to crack completely during the first cycle it might crack during second or third cycle of the boots. Is this something they pay extra focus to during thechnical courses?