Single-track roads with passing places are common along remote coasts and confuse visiting drivers more than any other road type. The convention governing them is simple and largely unwritten.
The bays are part of the carriageway
A passing place is not a lay-by. It exists so that two vehicles travelling in opposite directions can clear each other, and it is the only point on the road where that is possible.
Stopping in one to admire a view or take a photograph removes it from service, and on a road where bays may be several hundred metres apart that has real consequences.
Local drivers treat this as a straightforward courtesy, and the irritation visitors sometimes encounter usually traces back to a bay being blocked rather than to hostility.
The convention decides who moves
The vehicle nearest a passing place gives way. If the bay is on your side you pull into it; if it is on the other side you stop opposite and let the oncoming vehicle use it.
Crossing to a bay on the wrong side is not the practice in most places, because it puts a vehicle on the wrong side of a road with no visibility.
Reversing to the last bay is normal and expected. Judging distance to the nearest one behind you is part of driving these roads competently.
Overtaking uses the same bays
A slow vehicle is expected to pull in and let faster traffic past, which matters more than it sounds because the road may be the only route to a ferry or a hospital.
A caravan or a vehicle driving cautiously can accumulate a substantial queue in minutes, and clearing it costs the driver almost nothing.
Watching the mirrors is therefore a larger part of the task here than on a road where overtaking can happen anywhere.
Signalling is done with light and hand
A brief flash of the headlights on these roads generally means the other driver is holding position for you rather than that they are about to move.
A raised hand as vehicles pass is near-universal and worth returning, since on a road with few users the same drivers will meet repeatedly across a day.
Because conventions differ between regions, watching what local drivers do for the first few miles is more reliable than assuming the practice from home applies.
What makes these roads genuinely difficult
Surfaces at the edges are often soft, and dropping a wheel off the tarmac into a peat verge is the most common way these roads end a journey.
Sheep, cattle and deer use the road as freely as vehicles, particularly at dawn and dusk, and they do not move predictably when a car approaches.
Progress is slow by design, so a route across a single-track section should be planned by time rather than by distance, and the time allowed should be generous.