4/4 time signature forces bars on a line

Please see attached demo
DemoTimeSignature.dorico (567.6 KB)
In bar 5 there is a 4/4. Is it set to something I don’t see (or know) since entering 4/4 will keep the bars spread out while any(?) other time signature will merge then, as they should be? I cannot find any obvious setting that say “Keep these bars on the same system”.

If you go to Engrave mode and add a system break after bar 4, those bars will stay together on the first system, whatever comes after.

But it’s much better not to worry about layout until you’ve entered all the music. The subtleties of Dorico’s casting off can be confusing in borderline situations such as this. If you never want a partial system at the end, you can turn off Layout Options > Note Spacing > Only justify final system … But actually the partial system is a clue that you can get a better looking layout with one or two judiciously placed system breaks.

Yes, but I was wondering why “any other” key signature but 4/4 would reformat it. It is not a serious music file, I was playing around with meters and this happened and I could understand why. It seems to be some algorithm that causes this to happen for 4/4. I’m sure there is logic to it, I just wanted to learn why. With more “music” on the page, I guess it will format better.

Did you try equivalent time signatures in terms of beats, like c or cutc? Because they don’t change the casting off either.

I would strongly suspect it’s a case of note spacing calculations making a best guess at casting off, based on the preceding and following beats, and how many beats need to fit into each bar, ie how many beats until the next barline, which Dorico generally prefers to put at the ends of systems (rather than splitting bars at system breaks). Or simply that when you change the time signature to one with a different number of beats, you’re changing the total beats in the flow, which prompts a recalculation.

As Mark says, the fewer the bars in a flow, the less material Dorico has to work with.