A straight threading on 40 shafts offers a wealth of possibilities, without ever rethreading the loom. Repeats for plain weave, 4-shaft weaves (twills, double plain weave, basket, etc.), 5-shaft satins, and 8-shaft twills and satins, and 10-shaft satins all divide neatly into 40.
Other conveniences come to mind. Imagine a two-block pattern of reverse twill on a 40-shaft straight draw. You could have this:
or this:
or this:
You could choose any of the above without rethreading your loom; the decision would be based on the visual effect you’re aiming at: large repeat or small repeat.
Disregarding for a moment the issues of yarn diameter and sett, you could also choose a 5-end satin, and get this:
or this:
or this:
All divide evenly into 40.
You could also simulate a 13-shaft summer & winter point threading, and get the following draft (treadling & tieup version is shown, followed by liftplan version).
And to drive the point home, here is the same design on a 40-shaft straight threading:
I hope this leads you to think of all the ways you can use a straight threading on your own loom, whether 8 shafts or 88 :-)