Reset spacing over XXX bars

Is there a way to set the spacing to “redistribute over X amount of bars”? If I put in a system [frame] break in a specific location [start of a new passage or section], the results are pretty random. Is there a way (besides manually inserting appropriate page breads) that this would be propagated automatically?

Once you’ve added a system break (or frame break) you can select it and tick the “wait for next” property in the bottom panel. That tells Dorico to keep adding to the existing frame or system until it reaches another manual break. If you prefer, you can use the “make into system” or “make into frame” buttons, which do exactly the same thing but in fewer clicks - you start by clicking the note where you want the page to start, the Ctrl/Cmd+click the final note or barline you want on the page, then click “make into…”

There’s also all manner of things you can do with Note Spacing. You can loosen or tighten it globally from Layout Options, but you can add a Note Spacing change anywhere you like by selecting an object on the page and then going Engrave > Note Spacing Change.

I should add that this spacing is the result of adding a system break at the double bar at the end of the screenshot (added to facilitate page turning). It would seem that music on the previous page should respace itself accordingly, without needing to add extra system breaks or frame breaks.

Right. Any other breaks going on?

There was a system break at the start of the previous page (one before the one shown). That page has even more measures on it than the first one shown. The page not shown has 9 bars, the first one shown has 7 bars, and the last one shown has 2 bars. Can’t there be some kind of automatic spacing of bars between “this system break” and “that system break”? I can do it by manually inserting appropriate system breaks, but automatic spacing would be nice. (It seems to me that Sibelius does this – that is, instead of using the smallest possible space per system, it makes use of ALL the space available between system breaks if they are present).

I’m not defending what Dorico did, but there is a general problem with software trying to “optimize” this sort of layout. The program has some numerical measure of how far a possible layout is from the ideal situation, and if you force it to do something “bad” (in this example, putting 9 bars on two pages where the default spacing would almost fit them almost on one page, judging by what you said about the previous page) any possible split is measured as almost equally bad, even though from a human point of view some look much worse than others, and the program ends up making what looks like a random choice from “almost equally bad” options.

One way to nudge Dorico in the right direction is to use a Note Spacing Change for the whole flow (or at least for the last few pages) either to make every bar a bit wider and fill up the space without the need to stretch them so far from their “ideal” size - or to make the bars a bit narrower and use one less page.

FWIW Sibelius also used to make a mess of this by only stretching out the last two systems of the score to fill up the final system - this often produced horrible looking pages when there were several systems on a page, with maybe 7, 7, 4, and 3 bars on four systems on the final page rather than 5, 5, 5, and 6.