When I tried to shoot lightning with a film camera I was much more successful. I would set the camera on a tripod, aim it in a like
Y direction, set the exposure manually and wait. As long as my shutter speed was not too short I could punch the cable release when I actually saw lightning. Often enough I got some on film.
With my 5D MKII I'm always just a tad late. The latency between punching the cable release and opening the shutter must be longer with the digital camera.
So after getting frustrated missing strike after strike, I put the camera on continuous shooting and blasted away. I took 160 photos and 3 of them caught some listening. Only the one I posted was worth anything and even that's not all that great.