On roads with a lot of fast traffic, such as Ortega Hwy, I recommend waiting for the legal maximum of the five vehicles. Otherwise you could be stopping every couple of minutes. Someone just appears immediately after pulling out on the road again. If the road is less traveled I'll pull over sooner and let one or two vehicles pass. It is a balancing act. Courteous driving, law abiding, but not so hyper you're pulling over every minute or two to let someone pass.
And I agree with cmeade-look for a safe marked turnout, or at least one where it doesn't take heroic maneuver to get into. Some of these shoulders or wide spots are inadequate to pull into, brake into, or get completely off the highway.
