New Task Stat (avg completions per day / week)

This would be useful for me in a particular situation. I have some tasks with custom recurring periods like 3 or 4 days. However, some days I can't get to them and they have to be pushed back a day, because if I use the "Skip" function it will only recur after another long period, which is not what I want.

So, if we had this sort of task stat which simply averaged the completions over weeks or months, it would be a better way to measure the productivity of these sorts of tasks, because completion rate doesn't take into account tasks that are rescheduled.