there ought to be analyses or points where one realizes one has been too pessimistic and increases the probability

Some of my points seem unlikely enough now that I'll probably remove them. For example:

• The life insurance company does not pay out
• The cryonics company is temporarily out of capacity

One could also break a step S with X% probability into several steps that combine to less than X% probability if after looking at all the ways S could happen you decided that they combined to be less likely than you originally thought S was.