Yes. If I may interpret Heinlein, he wasn't saying that you need to be an expert in each of those things... he was saying you should be able to do it.

You still can be an expert in some things too, as long as it's not at the expense of those things.

(I'm not saying I agree; I don't entirely disagree or agree. I'm just trying to explain what he was saying, as best as someone else can divine his opinions.)