From the preliminary data I've collected (both on this and various fora, as well as through private research), I've come to notice that ROCOR, OCA-Western Diocese (esp. "Russian" old calendar parishes) and some Antiochian and Serbian parishes disproportionately predominate among parishes with very frequent Divine Liturgies, Vespers and/or Matins at least 4x a week, etc. (For the record, I now have some 40 parishes and cathedrals in my list, that have regular divine services -- excluding special feastday ones -- at least 4 days of the week). In also notice the apparent absence of GOAA from the list.
I'd like to know why "Russian" parishes would seem to be more likely to have frequent services compared to, say, the Greek Orthodox. Please understand that this is just my observation on raw data, and does not constitute any negative judgments on anybody.