It's not only the length of the sections, but the spacing between as well. As you saw my Z6 Trout which is made of 6 sections progressively all getting smaller. The action was much like a snake at first, due to the spacing I had between the sections. Once I minimized the spacing the fluid fish like pattern emerged. So IMHO, it has to do with both, segment size with the spacing distance being a major factor.
When the spacing was greater, the lure would fold into a "U" shape, but when spacing was smaller the bait formed more of an ARCH, and seemed to swim better.
Just my 2cents!!!
Video of action
Video of 12" Z6 Trout Swimbait - Photobucket - Video and Image Hosting