Mind you, I did feel some of them were quite legitimate, especially stuff like fewer buttons for style fills, so auto fill is the main way that’s used. Yours is the system that I prefer, and Roland went that way, but Yamaha users (and Korg, I think) have a system where each fill has its own button.

Quite honestly, in normal use, auto fill gives the smoothest most natural transitions, but quite a lot of Yamaha and Korg users create special ‘songstyles’ where each fill is actually a segment of the song, just like the variations. Not being able to call up the fills in any order you want because there’s no panel button for them definitely complicates using them that way.
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