Thank you, this is close to what I was looking for but there seems to be much fiddling involved (probably due to this function not planned for this usecase).
Indeed, I already have parts written on 7 different staves :
1a. The option to remove staff only seems to work with some instruments (piano) but not others (harp, flute, percussion kits, etc…). I can remove bars on piano but not on flute, etc…
1b. If everything needs to be pasted to instruments where “Removing staff” option work, we loose the ability to hear playback with desired sounds (less problematic since it is score reduction, but still).
It does not seem possible to hide an individual bar or a group of adjacent empty bars : it either hides all the staff or all the bars to the right of where you clicked (even if there are notes after). So that you then need to use “Add staff” option to recover the non-empty hidden bars (and this only works if you have not hidden the adjacent staff, otherwise you would have to unhide it first, which could quickly get messy !).
Finally, an automatic way of removing the empty bars (those with rests only) would be ideal, as with the “Hide empty staves” option.
A workaround for score reduction with hidden empty bars could be (I’ve yet to try this) :
a. Create a layout with only added bars from a piano staff for example.
b. Write all your parts.
c. Assign shortcuts to “Add staff” and “Remove staff”.
d. On each group of adjacent empty bars : Use the “Remove staff” shortcut at the beginning of it, and the “Add staff” shortcut at the end of it.
I hope there is soon (or already ?) a way to improve this workflow !