which lighting technique is better

gradually shifting from 24/0 to 12-12 or just shifting it from 24-0 to 18-6 to 12-12

i go from 24-0 to 12-12 with no problems

but my question is which performs better. im pretty sure they're both effective

Just switch, man. They're not that smart.

If you want a slow light cycle change then it takes about 10 day's to effect change in their life cycle.

So what Im doing - reducing the light cycle 1 hour each day - is OK? Ive read a few 'horror' stories about people switching straight from 18/6 to 12/12 and the plants have died. Anyway, surely by trying to mimic mother nature as much as we can makes healthier plants?

yes it works, and is more natural, but is a pain to do and will slow down the growth of the plants (since they aren't getting 18 hours of light to grow in anymore, just 16,15,14,etc.), thats why most people just go from 18/6 to 12/12.
And, the words of few do not outweigh the words of many. If your plants die switching to 12/12 they were gonna die anyways.

I agree it's a pain in the ass but you really can just switch them from an 18/6 to 12/12 as well. My self it depends on how I am growing.

Ive read a few 'horror' stories about people switching straight from 18/6 to 12/12 and the plants have died

You've got to be kidding. The plants didn't die because of the change in light schedule. They died because of something else like switching to too much bloom nutes, or ...