Is it standard to fill in every cross stitch square or is it acceptable/preferable to leave some blank? I'm planning to start a cross stitch project soon using one of the online cross stitch pattern creators so that I can use an image of my choice instead of finding an existing pattern that I like.

The pattern creator wants me to fill in the white space with actual white stitches rather than leaving the spaces empty, which is what I usually see in cross stitch patterns. I'm guessing that it may be due to a failure in the pattern maker - it is programmed to fill in all spaces - but I wanted to check.

What are the benefits of filling in all of the white space, if any? Is it even standard practice ever or is it actually more common to leave the space white.

I know that not filling it in will save me a ton of time but if there's a compelling reason to do it, I might consider it more seriously.
All of the cross stich projects I've done did not fill in the background with a solid color. This is typical in embroidery -- the design itself is stitched in, and the base fabric is used as the background. Not only is this faster and simpler for the crafter, it helps the design stand out from the background both texturally and visually.



Sampler by Catharine Ann Speel, photo from the Philadelphia Museum of Art

The only exception I can imagine to this is a pillow or other item that might be handled; if you want to have a smoother feel to the finished project, fill in every square (particularly since cross stich canvas is often quite stiff). Again, though, this isn't necessary -- the two pillows I made that included a cross stitch pattern were much more for display than cuddling, and therefore the background was left unstitched.