A power law distribution is roughly as easy to work with here as exponential. The blog post contains the power law results for this case, which are fairly easil

A power law distribution is roughly as easy to work with here as exponential. The blog post contains the power law results for this case, which are fairly easily obtained through a conditional average (conditioning on t > t_0). The important question you bring up is which is more accurate, which I don't have an answer for. But perhaps a reader has data on this. I will note that I compared exponential against some FOIA request processing data while back and thought it was okay, though I don't remember anything quantitative; see here: https://news.ycombinator.com/item?id=21032750 https://news.ycombinator.com/item?id=21032750 I think it's likely that something with more parameters like a log-normal distribution would be better than either, but intuitively I doubt you'd be able to get simple equations for the mean remaining time out of that. One problem with the power law model is that the expected duration at t = 0 is 0. The exponential model does not have that problem. You could fix this for a power law by not having power law behavior for short times.