I'm too impatient to start from scratch...and it takes a long time, and careful playing.
What I did was get a number of styles that have interesting/useful parts (pads, chords, phrases etc.) in them, store them in a folder, and use them as donor styles.
I reprogram my three Intros and often use them as extra variations or stop/fills, again using parts from other styles.
Most times, all a style needs is a few changes to smooth out the transitions from part to part.
It is pretty much a fact that a manufacturer's style programmers use a software program/sequencer to make accompaniments, and download from there.
I know of very few arranger players (of any brand) that are making high quality styles (entire styles) from scratch. Bert could probably do a nice job, for sure, but not many are at his level of playing expertise.
BTW, style programming can also be done in STEP mode (not in real time), by entering notes and chords.
Still too tedious for my liking.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.