As far as purifying one’s own mind, I agree we should try to meet all 4 aspects of right speech as well as the making our speech like that outlined on this ATI page, like in Ven. Dhammanando’s post here, we should try to answer questions right (AN 4.42), and we should try to live up to all the other teachings on speech that we haven’t covered.
Of course this is very hard to do, but we should try. Drops in a bucket eventually fill it up.