Good question, RAW i agree but that would mean that in a single player game only that first cube would try to connect/move forward, while the 2nd blocks the hub (blocking others from appearing) and keeps the borg danger quite far/limited.
I tend to move them up as far as possible and from the last system place a new lane if possible.
I suppose in a solo game it doesn't matter how you do it as long as you are entertained.
In a competitive multiplayer game the rules have to be clear however. In such an environment the only way is to play RAW and in this case RAW are unclear. Until we get official clarification house rules are the only way forward. My suggested house rules are on the files page and I'm hard at work rewriting the entire set of STA rules to be clear and concise in every regard.