It's a minor difference between getting the carotids or not, sometimes the rope works sometimes it doesn't, either way I always stand up. My climbing rope doesn't lock in place i've noticed whereas my nylon rope does, thus if I follow through I feel more confident with the nylon rope's knot holding when I start convulsing.
Partial suspension recreates a blood choke that is done in grappling (mma), the difference is that the rope never lets go, that's all it is. Having done bjj in the past getting choked by another person doesn't actually hurt at all, the rope normally hurts more as it's thinner and sharper than an arm.
No I think I started convulsing and moving around and moved off of my arteries. It's hard to explain but I was laying in an awkward position, which was hard to balance
What ligature did you use? a towel? I've read this happening a few times, it's too bad there's no footage of such incidents. What makes you think you were only out for 30 seconds versus say 3 mins? Any lasting damage?