I have the needed materials for an emergency exit in the back of my car and just knowing it is there if I need it helps my stability a lot.
I know that no matter what happens, if the worst thing ever came at me out of nowhere like it has before, I at least have the ability to escape the suffering.
Without that knowledge I would feel trapped by existence itself into having to endure any possible event that brings unbearable suffering onto me, and my baseline anxiety would be constantly higher for it.
I don't intend to use this emergency method. When I CTB I would rather use a more reliable, instant method of death, but that takes planning, preparation, and waiting to get right; so it's purely there for if I'm blindsided by something I cannot take again. The thought of having to do all that planning, preparation, and waiting while in unbearable suffering makes me extremely anxious, so it's calming to me to have this kinda "backup plan" if I need it.