A bit of both Levad.
I drive and cycle almost exclusively on singletracks. In a car I pull in to let people past but I don't pull in where they can't see far enough ahead to safely go past. I don't leave it to long though, nothing worse than being stuck behind a vehicle who won't move over. If the passing place is on your side, pull into it, if not stop opposite.
On a bike I try to time it so they can go past as I move in and stop pedaling. I hardly ever stop unless there's a few cars to get past or a big vehicle, I particularly try not to lose momentum going uphill, so I may make people wait then. Cars coming towards me are different. On narrow sections I take the road but on wider ones I'm quite happy for oncoming vehicles to come past slowly, same as in a car really. I may take the road initially so they see me and slow and then move over.
Safespeed on singletracks? Depends of course on the road. Most visitors here drive at around 30. They are often in the wrong place on the road going around corners, overshoot passing places and don't pull in fast enough. Consequently I drive slower in the summer than I do in the winter.