Just cut some box joints by hand (used a band saw to make the straight cuts in). It's almost like dovetails but easier.
Why would I do that instead of using the TS or router? A few reasons.
First, I like hand tool work and tolerate power tools.
Then there is the chipout problem with cutting them in plywood.
With a jig it is easier to make a mistake and cut one wrong.
Last time I made a box joint the jig didn't work out so well so I would need to make something better. Not a big deal, just one more thing.
Worked out well and not too slow. Doubt if I will ever mess with a jig again.