I game across this question when I tried the new feature to hide staves from multi-stave instruments (which, btw. is not fully functional in case of a single player who plays two different multi-staff instruments like, say, piano and marimba- covered by someone else in another thread).
Am I alone in being a little puzzled by the fact that some functionality is only available in galley view- like the switch between the different instruments of one player? I find this a little cumbersome, and I would really wish for some kind of key shortcut or UI button/switch that instantiates instrument switches, instead of only being able to instantiate that by inputting notes into the second instrument, which only can be done in galley view. Or open up for somehow making all the instruments visible in page view. I may be alone with this, but I find working in galley view to work against what Dorico otherwise does so extremely well- replicate an analog way of composing (I actually praised Dorico for that right when I first got it, and I still think that it does a great job in page view). When working with pencil and paper, I use sheets of paper, not an endless scroll, and this makes galley view pretty weird for my taste- kind of like having to wind a tape to the beginning to check what I did there.