You have two options within the fill's settings, at the bottom of the dialogue in my image below.
Scale with Plan (Model size) will mean that the distance between lines will alway be the same physical distance, no matter what scale your view. If the lines are 5mm apart (in the model) at 1:1, they will also be 5mm apart at 1:100. Therefore at larger scales the lines will be close together. This is handy for things you want to show actual size, like concrete masonry or paving, for example.
Scale independent (Paper size) means the distance between lines will always LOOK the same, no matter what scale your view. So if your lines are 5mm apart at 1:1, they will appear on your drawing as 5mm apart at 1:100, 1:200 or any other scale. This is good for graphical representation, like your diagonal fill for brickwork, at differing scales.