It's a good idea, the winter season bit, but no, Rat, it doesn't mean you have to go through a certain number of contaminated ops. I'm sure that is the intent, and it would be useful, but chance has a lot to do with whether it actually happens. Some bases do numerous flights into airports with hard winters, most bases probably, but some only have one or two routes that might do so and perhaps to airports that are well geared up to cope so the issue is well mitigated, losing that training benefit. Then there are the bases that will suffer the conditions directly, like Skavska and Kaunas. I wouldn't fancy being based in either for winter!