Just to add to Dave's post,
We had a discussion via PM and this really is one of my pet hates when buddying
Having to look around to see where a buddy is gets right on my goat, it is so much easier to just glance to the side and just see them.
Don't get me wrong I don't expect to be bumping into them every 2 minutes but off to the side is ideal, A buddy at my feet while I am finning away from them has a lot less chance of getting support in the event of a problem than one 3m to one side (distance is obviously dependant on conditions and comfort factor

). It is also naturally easier to check the buddy to the side and therefore checks will be more frequent.
Dave, Don't forget to always introduce buddies to the swim side by side signal (I point both index fingers and then bring the hands together so the fingers are side by side). No matter what you agree before hand, it is suprising how often it needs to be reinforced under the water.
Daz