Just to add a little recent experience in VMC on Tuesday.
I was flying my glider over central Wales, just south of Welshpool, in the cruise at c. 3800' AMSL, cloudbase c. 4600', heading approx 180. And low and behold I spot an aeroplane at approx 10 o'clock and about 1NM away on a course that will cut across my path, probably about 200' below me. So I think, 'let's see if he sees me' (I am ready to taking avoiding action). I waggle my wings quite markedly several times. I turn a bit left and then right. But the aeroplane (Cessna 180 or similar) just keeps ploughing on without change of course, speed or height. Of course he flies underneath my level (by approx 150') about 1/4 mile ahead (I slowed up by c. 20kts to ensure that).
Looking out or head in cockpit looking at all the gizmos?
That compares with last Thursday in the same general area when I heard (you always hear them first) a fast jet. I spot him to the left at about 2 NM and roughly same level I would guess but tracking across the front of me - and he spots me because he turns left in a climbing turn. Waggles his wings to acknowledge my presence. Tornado. I was prepared to drop down below his level if necessary. This confirmed my impression that fast jet RAF pilots do look out a lot, borne out by my experience some years ago of getting a back seat ride in a Hawk trip over Wales. The pilot then, despite being very busy with the task and everything else, was eagle-eyed with his look out. I asked him after the flight what proportion of his time on the flight was head in cockpit. Less than 2% he estimated.