It's a very reliable method and it is surprising that with the amount of publicity mentioning this either in passing or as a direct cause for a further investigation that it remains effective. After all, you'd imagine that wanna-be fraudsters would 'Benford-Proof' their numbers.
This is a very hard problem. Not only do you have to find a distribution that follows the law, the numbers still have to make sense in context (changing a 1 hour consult/doctor visit to a 9 hour consult). With election fraud you are usually up against a state statistician who at least tried to 'Benford-Proof' their numbers, so then the challenge is to find patterns of this Benford-proofing. For instance, Benford's law can be extended to the second or third digit, exposing the 2009 Iranian elections: "The data give very strong support for a diagnosis that the 2009 election was affected by significant fraud" https://en.wikipedia.org/wiki/Results_of_the_Iranian_preside...