Bridge "attachment" so small, why?

So I've been printing the 5mm cubes calibration [www.thingiverse.com] and when it comes to do the bridge my Prusa only starts the bridge what looks like a layer width (0.4mm) from the edge. And finishes the same. If it were to start 2mm back from the edge I feel as though it would "grab" better and stick to the other side better too.

Any reason why the bridging only joins on such as small surface edge?

I'm also having trouble with this. I am using a home-made nozzle on my prusa, and cannot bridge at all - the edges of the bridge barely touch the walls (and often don't touch at all) resulting in extrusion into thin air.

I'd love the ability to tweak the spacing, such that bridges overlap the layer below more.

I also have the bridging problem, sometimes it works fine and sometimes it's nowhere near right. Sometimes rotating the part will change the tool path and fix it, sometimes not.

I panicked one day, while printing x-axis ends it started spewing into free air, so I stuck my finger under it to support it until the other end attached. It was a little warm but it worked and the bridge looked fine after a couple layers over the speghetti. I don't recommend it, but I would have lost a lot plastic had I aborted the print.