Jose wrote:
The reason I mention this close encounter is that I have always been
hesitant about how well I can spot aircr.................

I too have to work hard to see other traffic from my 172 & I know that
some of my friends are better at spotting traffic than I am. Perhaps
it depends on our individual eyesight when the eye lens muscles are
relaxed. Supposedly the eye should then focus at a far distance, If
there is no background clutter, such as only a hazy sky, the best
answer would be to get a good pair of prescription sunglasses, cut for
best visual acuity at infinity - even if we don't wear glasses
normally.

On the other hand, every serious potential near miss I have ever
experienced involved a high performance aircraft that never saw me, and
under the technical rules-of-the-road should have yielded to me.
Pilots that I've observed sweeping out airspace at a high rate of
speed, seem to spend proportionately more time looking at the panel
rather than outside. The J-3s etc never give collision trouble.