unless you run the statistics script at the last second of the month (ok, technically, after the last change before the end of the month), you will be missing some actions' statistics.
likewise, if you say, don't generate statistics for a complete month, the statistics scripts will not back-generate statistics for that month.
this is what cairo does, so i guess i'll set it to enhancement, but i'm beginning to wonder when i should set things to enhancement and when i should set them to deferred.
Indeed that is Cairo behaviour. I usually run the stats at the beginning of the month for the previous month. See docs in TWikiSiteTools#Generating_statistics_manually_b.
A "nice to have" is to automate that.
Undeferred, post Dakar CC