EDITED (sorry for the length, but I cover a lot of ground):
Actually, my piece is divided into different movements. Rather, I think my use case is distinguished by the fact that I’m using Dorico as a (sometimes collaborative) composition and arrangement tool, not as a way to generate parts for live players. I simply don’t have the option to hire those kinds of resources. So playback and export to other programs (esp. via “portable”, editable MIDI or MusicXML files) is a higher priority than the ability to generate professionally engraved parts.
So, yeah, flows make logical sense to me as a way of structuring a longer piece. But as currently implemented, they seem to be interfering with my ability to share an entire multi-movement piece with colleagues who might be using other software.
And that’s why interoperability – the ability to flexibly generate portable output – is so important to me. Right now, it’s a challenge to transfer a Dorico project to, say, Ableton Live, or even a common MIDI media player like VLC. It’s not a dealbreaker if a piano has a brighter sound when a MIDI file is played back on a different computer with a different MIDI synth. But unexpected instrument substitutions, like piano for bass or tom-tom for tuba (both real examples culled from my current Dorico project) are a problem. Exported drum tracks are even more unpredictable unless I stick to a limited GM drumset.
To be fair, this isn’t solely Dorico’s problem. I understand that it’s a common complaint – and MusicXML doesn’t seem to be the answer.
FWIW, there are a few applications that are better at generating output that plays (more or less) correctly in other applications. But the only first-tier product that does this significantly better than Dorico for me is Finale – which was never a contender for me for reasons you’re likely well aware of. Notion and MuseScore, despite lacking key functionality, seem best at exchanging content with other programs. I keep copies of those programs on my system to help resolve translation caused by other programs. Sometimes importing Dorico MIDI output to Notion or MuseScore and then saving that program’s output in a portable format lets me generate a file that others can play & that sounds much like what I composed in Dorico.
Re: “arbitrary,” we may need to disagree on that one. Speaking as an ex-software engineer, it seems that it would take little effort to add a check box to the MIDI Export window that says “Export selected flows in a single file.” From my perspective, in fact, not supporting this option is actually inconsistent with Dorico’s audio-export functionality. So it doesn’t seem logical to me.
Now that I’m on the topic, I’d like to also suggest the ability to generate a PDF, MIDI file, or MusicXML output that contains a range of bars (or even an arbitrary selection). Similar to the way that Word or Adobe Reader lets you select a Print region. If, for example, I’m working on a tricky passage in the middle of a longer composition, it would be nice to be able to email an audio, printed, or MIDI copy of that passage to a colleague for comment or redlining. Right now, I can duplicate that feature by first importing Dorico output into a DAW, audio-editing program, or even the pro version of Acrobat. But it seems like this would be a simple feature to implement as native Dorico functionality.
So our main disconnect, I think, is that I’m primarily using Dorico as a (sometimes collaborative) compositional tool, not as an engraving program – not to say that Dorico’s outstanding engraving features aren’t tasty icing. So that’s why, from my perspective, the program seems limited in arbitrary ways. I don’t mean to demean your design decisions or the underlying concept upon which those decision are based. And I don’t believe that my suggestions would bloat the program or dilute its focus. In fact, they might make Dorico more attractive to a whole class of old-school composer users like me, who are looking for a tool to help to facilitate score-based note-by-note composition and orchestration – rather than manipulating beats and loops in a DAW. I’m more like Wendy Carlos than Billie Eilish.