% Your own madrigal accidental rule...
#(define-public (my-madrigal-accidental-rule context pitch barnum measurepos)
  "Here comes the description. This style is an exact copy of
  teaching-accidental-rule and needs to be adjusted.
  Original description:
  an accidental rule that typesets a cautionary accidental
  if it is included in the key signature AND does not directly follow
  a note on the same staff-line."
  (let* ((keysig (ly:context-property context 'localKeySignature))
         (entry (find-pitch-entry keysig pitch #t #t)))
    (if (equal? #f entry)
        (cons #f #f)
        (let* ((global-entry (find-pitch-entry keysig pitch #f #f))
               (key-acc (if (equal? global-entry #f)
                            0
                            (key-entry-alteration global-entry)))
               (acc (ly:pitch-alteration pitch))
               (entrymp (key-entry-measure-position entry))
               (entrybn (key-entry-bar-number entry)))
          (cons #f (not (or (equal? acc key-acc)
                            (and (equal? entrybn barnum) (equal? entrymp measurepos)))))))))

\relative c' {
  \key es \major
%   #(set-accidental-style 'teaching)
  % is the same as the following.
  #(ly:export (set-accidentals-properties #f
                                    ; automatic accidental rule:
                                    `(Staff ,(make-accidental-rule 'same-octave 0))
                                    ; cautionary accidental rule: (might want to put this to auto-acc and set cautionaries to '() ??)
                                    `(Staff ,(make-accidental-rule 'same-octave 1)
                                           ,my-madrigal-accidental-rule)
                                   'Staff))
  es es g e 
  es g es e |
}