I am a good Yekke and I never knew Yiddish when i was at home. Even in a high school were most of the rebbes were chassidish [although we weren’t], i only picked up very little yiddish. I knew less than the basics when i came to yeshivah, where all the shiurim are given in yiddish.
Because the shiurim are on the gemoro, and magid shiur uses the loshon gemoro in most sentences, there is very little that i need to actually know. Then an important ???? he will say in English anyway because it is easier to be ????? in English.
By now i can understand almost any Gemoro Shiur in Yiddish. But i still can’t speak a word of it!