I'm a big believer in maners, but job one is to obey the law for everyone's sake. Sure there can be particular occasions where one has to do something in the interest of immediate safety that may not be legal, but most of the time the rules of the road are the correct starting place. Three abreast, even two abreast is going to be illegal most places, consult you local rules. If it's illegal and it's putting your non-safety needs ahead of others, it isn't good maners either.
AH, I'm not lecturing you because there may be different local customs, but here, cycling in the wrong direction is illegal, I don't believe it's really safe. That perception is based on the idea that crowding cars out of the way is safe , which is usually only true when one doesn't need it. In other words one gets lots of space until the driver has to push over because of the large object crowding him from the cyclist's blind spot, now he will come over and through the cyclist who may be already feeling a little too protected. Also consider cars entering from the side, they aren't looking for Wrong Way Waldo since he's coming from the wrong side. Also, what happens when WWW meets cyclist's coming the right way. Also the idea one is likely to be hit form behind is kinda baby, I'm not convinced that's the real danger zone. Anyway, I've been to the areas of this site where they discuss this kind of thing and I know the views are endless.