However, there are many exceptions to this rule. If one uses the offshoots of the date palm, the s'chach is valid. These are bundled together by nature, not by human hands. Even if he later binds these offshoots with a rope, it is still not a bundle. They are already one, and you cannot bundle them more.
In Sura, it was the custom for the merchant to bundle the branches of s'chach to make them of a standard size. People who bought these bundles would always untie them to dry. In this case, too, there is no concern that people will keep bundles on their sukkah, and it was therefore allowed.
The Talmud also find parallels between those bundles and the bundles of hyssop used in applying the ashes of the Red Heifer to clarify how many items constitute a bundle.
Art: Palm Tree at Bordighera by Claude Monet