Block size, when drawing, does not really matter. The block you draw at 11″, can be printed or used in a quilt design in any size. The same is true for all blocks from the Block Library.
The size of your block = Any size you want when printing or quilt designing. Block size is simply to help you draw, so you can size patches in your drawing.
To see rulers across your block, click VIEW on the top menu, and make sure Block Rulers is checked.
To be able to easily change the size, click VIEW on the top menu, and make sure Precision Bar is checked. You can quickly change block Width and Height, and the number of grid Snap Points, right on the Precision Bar.
Block size does matter when printing Rotary Cutting. To get the most accurate rotary cutting sizes, with the least rounding, size your block to fit the block grid style.