I frequently mark sections with system boxed text like so:
However, now I have to manually check every instrument part because invariably the text will hang past the end of the staff in some places like this:
The same happens with any tempo indication that’s not a simple short word or two, and other text.
Is there a way to get this to behave better automatically? Thanks.
Stephen, Dorico doesn’t handle this automatically - so one has to check these by hand still.
At some point in the future there probably will be a cleverly baked in functionality for this, but until then we’ll have to stay patient.
I’d put in a System Break, so that the new phrase (and rehearsal mark) starts on a new line.
I do hope this is something that can be fixed at some point. It feels so unlike Dorico. Adjusting margin overlaps make me feel a bit like I’m stuck back in my Finale days.
While we are waiting for an automatic functionality, first step could be to give Rehearsal Marks a property to place themselves to the start of systems. 
just contemplating…
Sure, I can do that, but I have to manually proof and edit all 35 parts for such silliness. This is the kind of thing I was hoping to get away from with Dorico when I switched from Sibelius.
Stephen, there are things one has to do manually, when proofing score and parts. These are of course page turns, but also things like the ones you mention above. In a way it forces oneself to check as a human. This is always good, and it will also give each document a certain personal touch… Dorico in this regard is miles in front of its “competitors” - the final tasks are really marginal.
I’d like to comment on both sides of this issue. I support k_b’s position that this can be regarded as part of necessary proofing. But also the issue has been raised many times regarding long tempo marks, and Daniel & the team are aware of it.
One can find a few examples in published plate engravings of tempo marks split over a system break – it is generally awkward, both to engrave and to read. Currently tempo text is a font style rather than a paragraph style, so multiple lines are not possible.
Even when/if that does become possible, I don’t know how complicated or difficult it might be for Dorico to detect such text impinging on the right margin and wrap it appropriately in individual layouts. For example, I’m sure users would want complete control of preferred locations for line breaks.
In Mahler’s Das klagende Lied (I played it yesterday) there is a place where the tempo indication ‘Noch drängender’ over a multibar rest in the cello part was split over a page turn in the middle of the last word. In one of the early rehearsals it was puzzling to see the first bar on the new page marked ‘gender’. What??
I was more assuming an earlier system break (how I generally fix it manually), although being able to manually split lines would also help. Guess I’ll go with reduced font.
the final tasks are really marginal.
Oh, I see what you did there! 
This one is annoying (although I don’t see why there should be technical hurdles), but where I really pull my hair out is condensing choral parts. It’s so annoyingly 95% there, but the last 5% is a pain to fix.
Instrumental condensation is usually quite incredible, was even able to force a few instruments onto 3 or 4 parts on one staff for a couple pages where there was so much going on that vertically things went over. But choral tends to trip up over duplicate lyrics and other things. Would love to see that improved more.
I would advise against automatically condensing vocal parts.
As you have noticed, little things like different lyrics position add another “layer” to the complexity. If you condense vocal staves manually you will have much greater control on how to consider and solve these placements.
