I think the responses and conclusions can be summarized as "Square Hole but Round Peg". The basic nature of watch movement parts ie: gears, coil springs, date wheels, etc tend to be round. So the corners of a square movement are mostly not "functional" in a sense...unless you think WAAAY out of the box (or In The Box more aptly) like the Monaco V4 reviewed here by Amanico www.watchprosite.com or even MORE in the box like Behrens x Vianney Halter here https://www.behrenswatches.shop/blogs/posts/behrens-x-vianney-halter-unveiled-new-versions-of-kwh-limited-edition. But you gotta be willing to go absolutely crazy in your design process.