Exactly. To see why notice that in a curriculum you are presented with both a problem and a solution. You are encouraged to find your own solutions to many problems, but regardless of whether you do you are also presented with the correct (optimal) solutions. This removes inaccuracies in your thinking, which would otherwise pile up multiplicatively, yielding a log-normal distribution of the time needed to master some topic.
Designing and implementing a curriculum is probably a log-normal effort.