If you go into a coma from sn, you've likely progressed into severe Methemoglobinemia and if you are found a day later, you are more likely to be dead than alive, questions like this really can be answered if you just take time to understand how this method works from a medical standpoint and why so few people come of it alive because intentional attempts to ctb with sn are most likely going to be fatal especially the longer it takes to receive medical attention so if anyone even finds you a day later, they'll probably find you dead.
It does not take a few hours at all, there's been patients who've died on the way to hospital and even after treatment so this does not suggest it takes hours to die from sn, it's rapidly fatal for a reason and needs to be treated immediately, it's not something that can be delayed since it takes hours to die anyway.