If you can, reduce the distance between staves. And reduce system margins :
try smaller values in Document->Page Format ->Score.
You can reduce the size (%) of staves, the size of the system margins, etc...
To see the result, you need to go to the Page Layout tool, menu->Redefine pages->all pages.
MacOsX 10.9.5, Mac Mini Intel Core i7 2,7 Ghz, 16 Go Ram, Dolet 6. Azerty kb. Full TGTools. MOTU Midi Express XT USB, Roland Sound Canvas SC-88vl, MOTU Audio Express.