Mathematical language is not really well understood by many people. People could mistakenly use "regular monthly average" when they actually want the 'average per 30 days' but that doesn't change the meaning of those phrases, just as people creating about "stationery vehicles" does not change the meaning of "stationery" https://financefeeds.com/japan-to-reclassify-copyright-as-financial-product-paving-way-for-etfs/