I'm not sure if anyone has right of way on a single track road, and common sense and courtesy must therefore be employed. I don't know how well this system works in other parts of the country as these qualities may not be evenly geographically distributed but it usually works around here, perhaps with a hiccup in the summer time which may be due to the effect of the heat on otherwise perfectly reasonable dales drivers or it may be a function of the influx of folks from places where they are used to being able to rely on a sign or road marking to decide who has precedence, and where it assumed somebody always has precedence.
Traditionally the general etiquette is that the party with the passing place/gateway/turn-off/slighly wider section of road nearest to them or on their side of the road uses it to let the other party pass and it also makes sense that the road user who can most easily facilitate the passage of both parties does so. Usually a little bit of give and take on both sides is required.
In the case of two cars meeting head on this entails stopping, scratching heads, and then some general shuffling and reversing by one or both vehicles. In the case of a bike meeting a car , even in my local area with many miles of single track lanes and no purpose made passing places that I can think off, pretty much the only time I am unable to negotiate my way past an oncoming vehicle by ducking into a gateway or slowing down at a wider bit or road or just squeezing past, or allow a following vehicle to overtake, without both feet still on the pedals is when I meet something agricultural or military which is brushing the verges on both sides and I need to vacate the road entirely.
I don't keep count but I would guess I receive as many courtesies; people waiting at a road widening for me to pass or waiting the other side of a cattle grid or bridge for me to cross, as I extend to others so in answer to the original question therefore, I suppose statistically you would expect to be pulling in only 50% of the time, and rarely having to come to a stop, but if you are doing so more than this I wouldn't worry too much as you are just adapting to the local conditions.