The contemporary jazz musicians have developed a series of chordal cadences based on modes. George Russell's "Theory of Lydian Tonality" treatise is an example.

There are examples of chord progressions based on be-bop modes or some on "Lochrian" modes which are not historically part of the Church Modes. Lochrian or Lochryan is a theoretical mode based on the seventh note of a major diatonic scale. B,C,D,E,F,G,A,B. It is not found historically. Someon devised it because the original Church Modes were based on a "gapped" or Hexatonic scale which did not include the seventh note of a modern diatonic sacle.



Here's the deal with folk music and modes. There is no proof that folk music is based on early Church Modes. This is sheer speculation and inferred by academics who have an agenda. Cecil Sharp was trying to find English folk songs in America.
There is some evidence that this might not be the case. Many of the singing styles and fretless banjo playing styles of the Southern Mountains contain what some might call micro-tones or quarter-tones. If you listen to Appalachian singers, they tend to sharp the seventh degree of the scales (assuming that you listen to them with what we know of key-toned scales) and that the African-American based singers tend to flat the seventh tone from a "tempered" pitch. This kind of ornamental pitch-change is not found in Church Modes.

I think that "modality" is basically a reference to Early Music and has perhaps little relationship to folk music. You can of course write a stylistic "folk tune" in a Church Mode and call it a folk song if you want to.

A kind of consistency in so-called "out of tune" singing by ethnic American folk musicians has yet to be studied by ethnomusicologists.
I think it's safe to say that there are musical patterns that define an American approach to traditional folk music.

The study of the Church Modes however is useful depending on how you apply it. In music every rule was made to be broken and even Bach broke his own rules.

Frank Hamilton