Interesting, this makes me think of a process I am going through, where I have a couple of very wide tables where I feel a need to build fact tables simply to get a better understanding of the data and the domain they are from. I have already stumbled a couple of times as the groupings was not as expected at all. Think this was the last push for me to build those fact tables once and for all, to get an overview and also to be able to add my own inferred groups to the data.