Maybe you all know this already, but I take the risk to share it here 
In engrave mode, add a Note Spacing Change.
Switch to Note Spacing mode.
Undo, and then press enter.
Now you can edit the Note Spacing and at the same time see the fill percentage of each system.
Of course we have to use our eyes, but personally I tend to always want to check the fill percentage as well. In this way you don’t have to switch modes to check.