When you make a repetition by sketch, it gives you an occurrence at each point in the form of (*), so either you constrain the 1st occurrence, the one that drives the repetition without putting a dot (*) on it, by putting a line for example to be able to select the end of this line as a starting point. Either in the function you select the duplicate part in occurrence to omit. Personally I prefer the 1st method.
You can construct a construction line and you constrain the origin or other point of your part on the end of the construction line without putting a point see attached image and in the options see last selected image "selected point" instead of "center of the visualization cube"
I do use the sketch of the holes, and in the sketch-by-sketch repetition function, I don't have the ability to omit occurrences like you can do in an assembly.
To keep my holes, my first sweep (original threaded rod) and the repetition, I was forced to delete a body in the folder of the volume bodies.
The question is passed on to Visiativ, we will quickly know how to carry out this kind of design.
Another solution then in your mechanically welded you put your 1st threaded rod in transparency and then you put the one that is repeated on top of your 1st occurrence in the deleted state, not very glorious but functional.
Visiativ confirmed the "failure" of this function in this context: it is impossible to omit occurrences on a Part in repetition by sketch, and thus the creation of a supernumerary body.
The proposed bypass, less efficient, is a stupid linear repetition on 2 directions, which requires knowing the decomposition of the centers.
In my case, there is only one center distance (2 occurrences of drillings) but on more complex holes, it is certainly not tenable.