I think it was quite common. I just finished reading a book on L&H which stated that mode of directing was extremely common on the Roach lot in the silent days.
Of course, nowadays that style of directing is considered very bad form. I've heard stories of experienced actors being infuriated by young directors 'showing' them how to play the parts.
I recently worked with a young director who played out a make-up scene with a young actress to show the male actor how he wanted it done. Somehow, I think the director got more out of the demonstration than the other actor!
I'm curious about that too.
Sean
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'I & I, in creation where one's nature neither honors nor forgives. I & I, one said to the other, no man sees my face and lives.' B.Dylan