toan-hoang
Son
While I'm mostly in agreement with you in this topic, I think this example may not serve the way you think. As children, we're only given the basics of these topics, so it's no big deal to learn them at the same time. Note that by the time we get through university the variety of topics we study has narrowed considerably while the depth of study on each topic has expanded considerably, and those who wish to become teachers must specialize even further beyond that. I can dance on1 and on2 proficiently, but being able to dance proficiently is like having a bachelor's degree. The depth of knowledge required for teaching goes beyond that (which is not to say that one cannot specialize in both, but it is to say that one must put in the time to specialize in both rather than specializing in one and then depending on the fact that they can dance the other competently).
EDIT: It seems I was a little too late with this point and it looks like I just reworded what toan-hoang said XD
2nd EDIT:
I live in LA so yes, I have seen this (besides my own case). I've only seen a handful of people give up on it entirely. The important thing seems to be dancing on2 when possible (i.e. when you're dancing with someone who can do both just dance on2) to get the repetitions. In that aspect the part about doing a little on2 and picking it up was slightly off the mark. Look at it more like turning on faucets than flipping a light switch. If you have the hot water going but you gradually increase the amount of cold water then eventually the water won't be hot anymore. You don't have to stop dancing on1 completely (IMO and IME), but you do have to increase the amount of on2 dancing relative to on1 dancing for at least a while. 5 years ago out here reducing the on1 amount to 0 was pretty unrealistic.
Similar minds huh...

