Dear Lister Noble...
Agree with what you do. Coincidentally, I'm a Cub pilot (gave up on Tiger Moths as too draughty) and use the radio in much the same way.
Radio is a great help to be warned about other aircraft being around (esp. when in or close to an ATZ).
Having arrived at your post by the link you left elsewhere, I suspect that keeping a good look-out may well also mean having eyes in the back of one's head and under / over one's aircraft.
I can recall times when I couldn't see everyone who called downwind. Once by chance I turned left and saw another aircraft not too far below me directly underneath. Ooops.