Ask HN: Help find a post. Chart: time waiting action vs. time to fix action

Not so long ago, a developer published in his blog a simple X-Y chart in which, for a blocking task:

1) Given the time idling waiting for the blocker to finish 2) And given the number of expected occurences of the above

He calculated the allocated time to try fix/improve the problem

I've been unable to find the post. Any clues?