Do you ever get too comfortable when you're flying? I routinely fly from our airpark down to a neighboring private airpark to work on one of our project airplanes. The other airpark is "Private - Prior Permission Required" for landing. It's easy to get permission from a resident, and you'll find out that the preferred runway is 34, with right hand traffic, and CTAF Is 122.9. Knowing all that, it is easy to just assume that everyone else does as well, slip into a right downwind for 34 on arrival, broadcast intentions, and not really look around - because there is so little traffic.
Yesterday, I landed, and my wife came in about two minutes behind me... and a minute later, a big Cessna came in from the OTHER direction (Runway 16), with no radio calls. Someone else mentioned later he'd flown a left hand pattern (up against the mountains – not a good place to be). Bottom line is that if I’d been a couple of minutes later, or he’d been a couple of minutes earlier, we might have met head on halfway down the runway.
Its easy to blame him for not getting permission, not getting briefed, not flying the right pattern, not using his radio... but if it had gotten squirrelly, I'd have had to blame myself for putting myself into a position with higher risk by not scanning the ENTIRE airport traffic area for someone else.
Just one more thing to think about...