Again, true. As I was in transit and speaking hurriedly, I did rather change the subject. But as the OP, it’s my right to do that.
When I can sit down, I will watch those videos.
But from memory, I offered this as amusement. Kenji Alt said that you have to add cold milk slowly to the butter flour mixture when making bechamel.
So, to be mischievous, I consult Jacques Pepin and he’s got a video where he just dumps all the cold milk into the bechamel in one fell swoop. It’s all in the whisking. And Jacques doesn’t even use a whisk for omelettes and his mother’s cheese souffle!