Sorry I 've been misunderstood.
When I was referring to "organs" I meant any kind of musical instrument
(I was lost in the translation,that's how we call them in my language in short
)
A "fill in" can be always as long as one single bar in sheet music no matter what the rhythm is (2/2,2/3,all the rest rhythms) as you said.
If you don't press it in beat 1, is even shorter than a bar.
So in this, lets 's say "fill in bar", there can be a riff from an electric guitar,a small arpeggio from a piano,a G-C-E chord instead of a C-G-E chord of a pad, a brass that uses a note with the modulation wheel etc.
And every of these follow at least the basic chord types.
These things cannot be broken in pieces.
You can not have half playing of the arpeggio when you trigger the "fill in" at half of the bar (at beat 2 of 4/4, for an example).
If there is another way to make things work better just by using the Main Style part of the keyboard, I don't know.
I am not a professional style maker but if you miss the "right" spot I don't thing you can turn back time to hear the whole riff.
Maybe there could be programmed alternative shorter riffs that would play only in these cases?
If Yamaha could make it's styles to sound better but the engineer's don't do it because they get bored of making better styles,I don't know it either.
If I want variety in the style parts, I just keep adding registration buttons to the song.
Not an easy thing to do but to tell you the truth sometimes I don't really mind that much what the ...."guitarist" may have in mind to play in a single (or less) bar for the "fill in".
But sometimes I do care for a specific riff that's why I said it might be better to keep your finger down for sure by the end of the previous bar.