Endeavor has his beard on fire all the time because he's the most extra.
Also even if the training had been planned and he learned about it from Shoto---I can't even finish... he wouldn't care about Shoto enough to know what he was learning at school. He'd just assume it was "be #1" and leave it at that.
I have my own inside man theories but they're pretty much all against the grain of the common theories.