I do agree with that, but that depends what technique you are working on.
If you are a beginner and just starting to work on alternate picking, your best bet is to focus purely on that technique until you are comfortable with it. Then incorporate the other hand and make it musical. Eventually you could work on riffs, etudes etc that will kill two birds with one stone as you say.
My opinion of course, but I have used these methods to teach plenty of people with great results.
If you are a beginner and just starting to work on alternate picking, your best bet is to focus purely on that technique until you are comfortable with it. Then incorporate the other hand and make it musical. Eventually you could work on riffs, etudes etc that will kill two birds with one stone as you say.
My opinion of course, but I have used these methods to teach plenty of people with great results.