The other child thread helps to explain where my discrepancy came from. Most companies prefer to have a unified pay schedule, so if there are workers in the company that you'd expect to pay bi-weekly/semimonthly (such as hourly wages), the entire company will be put on that schedule.

My own personal experience has been in the post financial crisis tech industry, and I wonder if tech pays monthly more often compared to others (and if funding plays any role in that).