After a useful piece of advice on the RTCUK group that said you should clip to an 'O'-ring on your bridge rather than directly onto the bridge, I started to do exactly that. The rationale was that a carabiner will wear in the same place and abrade the bridge quicker than a ring that will wear uniformly all round it. Fair enough.
Well yesterday I was putting up a high hammock and had set up a Y-rig with two doubled ropes off the bridge. One was on my ring, but the other was clipped straight to the bridge. Because each leg was attached to anchors quite far apart, the tie-in points migrated to the ends of the bridge - but the directly-clipped one went beyond the bridge-end fittings.
This is not a good thing. Lesson learned. I'm buying a second 'O'-ring.