I found it takes the same amount of time to go from 0 to 50% completion as it is to go from 50% to 80%, and similarly from 80 to 90%. This means when you are a

I found it takes the same amount of time to go from 0 to 50% completion as it is to go from 50% to 80%, and similarly from 80 to 90%. This means when you are at 50% completion, you need to spend more than two times more effort to hit >90% completion. 99 to 100% takes an infinite amount of time.