What determines what scale the first view is

Hi All

What determines what scale is used on placing the1st view on a drawing.

Generally we us A3 size paper for single component drawings.

When I bring a part into the drawing I usually (but not always) have to go to the model sheet properties and change the scale so it looks better on the drawing.

For example on one part I brought it in and the scale was 20:1 so it looked tiny on the drawing.

So I had to change this to 10:1 to make it look better.

What determines the initial scale on placing the 1st view?

Thanks

Mark (SolidWorks 2015 sp2.5)

SolidworksDrawings And Detailing