I have found 9-patches from squares (instead of strips) to be anything but fast. All that corner matching, plus sometimes a row will look just fine until it’s connected to another row, and then it’s suddenly wonky.. “Just squares” is akin to straight line quilting, which many find hard and fiddly to do.
To minimize that, I’d choose a background color that is low-contrast, so that any slightly misaligned corners will be harder to find. Or go with one of the common no-match designs, where a rectangle is sewn to a square and rotated.
charlotte