I've done it all 3 ways. I like the look of the cornerstones, but it just kind of depends on the look of the blocks and how much fabric I have for sashing, and how much piecing together I feel like doing.

I am just getting ready to do my first quilt with sashing. The info is very helpful. thanks

Quilter's choice. But, I prefer the width for the long, continuous strips.

I find it always better to add to the side and then the bottom to each block. It seems to stay hold its shape/size better. When all pieced together I do just add one complete strip to the top and one side to finish.

Done it both ways but to be honest, I have found the width tends to makes me line up my blocks better. Otherwise I tend to have crooked rows going down.

I sew the vertical sashing strip to each block, then sew the horizontal rows and add the horizontal sashing strips as I go.

I find it easier to do the horizontal sashing first; then do the vertical. Doing the vertical last helps me to keep my quilt top square. I put the vertial sashing strips in the same way I do outer boarders - by using the center measure of the quilt as the average length and make each sashing strip the same, easing in fullness if necessary.
Marti in Missouri

I find adding sashing to each individual block FAR easier than dealing with long strips of fabric. And the blocks all line up perfectly.

Here is an example of what I'm talking about. The block was made, then a green strip went around the outside, then a red strip was sewn around the outside. Then all the blocks were sewn together.

This quilt is beautiful! I love the thin green border around the blocks. And I think I have the same green flip flops. ; )

A question about adding sashing fabric to each block- my sashing fabric is white (white on white). The seams are hidden in this quilt's red sashing, but I'm worried that the seams would show up more with my white fabric, and would look weird... :?:

On my baby quilts I do it along the width and then the right and left side the long way. But it is whatever way you feel comfortable doing.