@Juriaan said:

Still wondering why this is default on and not off ?

Because when it's off, if you duplicate/copy+paste Controls within a document because you want more of a particular Control or set of Controls, it doesn't increment the Control IDs of the new Controls. Copying Controls within a document and wanting them to get their own Control IDs is a more common use case than wanting to copy Controls between documents while preserving the Control IDs, which is why it's enabled by default.

@Juriaan said:

Mark as Solved.

 Just renamed the thread and moved it to "How To" ;)