Its not important what side you are on, just don't change lines suddenly. If a fast guy is passing you, stick to your line and he will know how to get around you.
NEVER change lines anywhere near or after a jump. Otherwise someone is going to get jumped on, or the fast guy will need to make drastic changes to miss you that will cause him to wreck.
Some tracks have optional jumps where one half of the track has an easier set of doubles or a table, and the other might be a tripple. In that case, stick to the easier option if you have no intention of jumping the tripple.
(Now a Red Rider)
I don't agree with the white line down the middle of the jump. If riders would pay attention to where they are going. The dividing white line would not be needed. I think most would agree. Hold your line and stay to one side. There is a new local track that has just opened here. The owner is planning on doing the divided white line. To the left you jump, to the right, no jumping. What if the best line is to the right? Now I can't jump the double. If I go out and practice on the track during the week, and my better line is to the right. Might that make the jump more dangerous for me and those racing around me? Also, most local tracks at best are maybe 20' wide. So now I'm racing to hold my position. My competition in front or behind of me only have to 10' to do the double. I don't like the idea, and think it is a recipe for disaster!
Mainly, I have to give credit to JohnyB for bringing this question to light. Thanks, it helps all involved be safer when riding. It is good to see someone asking for help when they don't know.
Lastly, I will sound like a broken record and say that slower riders should Hold Their Line when being overtaken. The faster riders know where you are and they should have enough skill and speed to safely pass you on a differnt line on the track.
Thanks again JohnyB.
One thing that is VERY important (ive had experience with this!!) DO NOT act like ur gonna do a double then let off right before you jump it! i landed on a lapper one time like this...wasnt fun pulling his footpeg out of my thigh....... :p